[time-nuts] Digital Scopes - suggestions
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I'm looking for a digital scope. Is there some obvious model(s) that I should keep an eye out for? I don't need one, so I'm willing to wait and I'm flexible on parameters. Mostly what I'm looking for is: reasonable (hobby) cost standard digital stuff: bright picture from a single event screen capture (GPIB or RS-232) I expect there is something in the 100 MHz range. I probably don't want to pay for a GHz front end, but I might if I got a good deal. Quiet is good. Running Windows is a minus in my book. (I'm not smart enough to keep a Windows box virus free.) Being able to see a 10 uSec pulse delayed by 1 sec would be good. -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Digital Scopes - suggestions
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hal Murray wrote: ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I'm looking for a digital scope. Is there some obvious model(s) that I should keep an eye out for? I don't need one, so I'm willing to wait and I'm flexible on parameters. Mostly what I'm looking for is: reasonable (hobby) cost standard digital stuff: bright picture from a single event screen capture (GPIB or RS-232) I expect there is something in the 100 MHz range. I probably don't want to pay for a GHz front end, but I might if I got a good deal. Quiet is good. Running Windows is a minus in my book. (I'm not smart enough to keep a Windows box virus free.) Being able to see a 10 uSec pulse delayed by 1 sec would be good. I bought an old hp1661CS logic analyzer on ebay for not a lot of money. There's a 16500 model for $280 up at the moment. These come with 2 x 1GS/s digital scopes as well as the logic analyzer function. They're not designed as scopes but they do a pretty good job. The prices for similar capability scopes are usually higher. Good luck Tim ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] QCM
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Gentlemen, again my question is a bit OT: Has anyone of you personal experience with QCMs (Quarz Crystal Microbalances) and give me a recommendation on a) what surface coating is suggested if the aim is to measure small amounts of humidity in clean air b) where such crystals may be supplied from in small quantities c) or if anyone is aware of a ready to go humidity sensor based on QCM technology Best regards and TIA Ulrich Bangert www.ulrich-bangert.de Ortholzer Weg 1 27243 Gross Ippener Germany ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Digital Scopes - suggestions
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hal Murray said the following on 10/24/2007 03:47 AM: ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I'm looking for a digital scope. Is there some obvious model(s) that I should keep an eye out for? I don't need one, so I'm willing to wait and I'm flexible on parameters. Mostly what I'm looking for is: reasonable (hobby) cost standard digital stuff: bright picture from a single event screen capture (GPIB or RS-232) I expect there is something in the 100 MHz range. I probably don't want to pay for a GHz front end, but I might if I got a good deal. I have a Tek TDS-2012 that I like a lot. Dual channel, 100 MHz and 1 Gsample, color LCD, very small and light. Comms (RS-232, printer, GPIB) is an optional module. Base price is something around $1200 new, I think. I think they've been around long enough that there should be some used ones out there somewhere. There are also several other models in the same series that vary in number of channels, speed, and monochrome versus color display. I still use an analog scope (Tek 2465B) for serious RF work, but the digital can't be beat for looking at PPS and general bench use. (My theory -- Tektronix for scopes, HP for everything else.) John ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Digital Scopes - suggestions
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi John I think I have the perfect suggestion for you. I spent 200+ hours researching scopes before I started my business, primarily because I am a cheap bastard. I finally found what I wanted, at the price I wanted. Please check out bitscope.com. I bought one over a year ago and it has paid for itself many times over. The support has been absolutely excellent. It is a PC controlled scope but it is external to the PC so it does not pick up noise.I bought the 310N, it has a built in logic analyzer, an signal out function and it can monitor two channels by multiplexing one. It can trigger from logic or analog. It runs on Windows and Linux. There are now Debian and Ubuntu packages for easy install and they are just releasing a control library. Together with my AEMC current probe I have used it to fix a number of difficult problems. I had to pay a 7% tariff to get it into Canada but shipping was cheap and the price is low to start with. I just checked the current price and it looks like it is $585 U.S Please don't hesitate ask if you have any questions. Bruce at Bitscope had been very helpful and sold me a great scope. I feel I owe him time considering the insane amount of questions I have asked him, of which none of them were due to shortcomings of his product. -Patrick John Ackermann N8UR wrote: Hal Murray said the following on 10/24/2007 03:47 AM: ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I'm looking for a digital scope. Is there some obvious model(s) that I should keep an eye out for? I don't need one, so I'm willing to wait and I'm flexible on parameters. Mostly what I'm looking for is: reasonable (hobby) cost standard digital stuff: bright picture from a single event screen capture (GPIB or RS-232) I expect there is something in the 100 MHz range. I probably don't want to pay for a GHz front end, but I might if I got a good deal. I have a Tek TDS-2012 that I like a lot. Dual channel, 100 MHz and 1 Gsample, color LCD, very small and light. Comms (RS-232, printer, GPIB) is an optional module. Base price is something around $1200 new, I think. I think they've been around long enough that there should be some used ones out there somewhere. There are also several other models in the same series that vary in number of channels, speed, and monochrome versus color display. I still use an analog scope (Tek 2465B) for serious RF work, but the digital can't be beat for looking at PPS and general bench use. (My theory -- Tektronix for scopes, HP for everything else.) John ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Digital Scopes - suggestions
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi Brooke I am not exactly sure. You can go into the uS range but I had better check with the Bitscope people about the exact details. I will forward this email. I am sure you will have an answer tomorrow. -Patrick Brooke Clarke wrote: Hi Patrick: They have an impressive line and I like PIC based products. Can you measure the period of a 1 PPS signal when the pulse width is on the order of 0 us? Have Fun, Brooke Clarke http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam Patrick wrote: ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi John I think I have the perfect suggestion for you. I spent 200+ hours researching scopes before I started my business, primarily because I am a cheap bastard. I finally found what I wanted, at the price I wanted. Please check out bitscope.com. I bought one over a year ago and it has paid for itself many times over. The support has been absolutely excellent. It is a PC controlled scope but it is external to the PC so it does not pick up noise.I bought the 310N, it has a built in logic analyzer, an signal out function and it can monitor two channels by multiplexing one. It can trigger from logic or analog. It runs on Windows and Linux. There are now Debian and Ubuntu packages for easy install and they are just releasing a control library. Together with my AEMC current probe I have used it to fix a number of difficult problems. I had to pay a 7% tariff to get it into Canada but shipping was cheap and the price is low to start with. I just checked the current price and it looks like it is $585 U.S Please don't hesitate ask if you have any questions. Bruce at Bitscope had been very helpful and sold me a great scope. I feel I owe him time considering the insane amount of questions I have asked him, of which none of them were due to shortcomings of his product. -Patrick ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Digital Scopes - suggestions
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I was wondering about that! :-) Patrick Brooke Clarke wrote: Hi Patrick: That should be 10 us not 0 us. Thanks Have Fun, Brooke Clarke http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam Patrick wrote: ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi Brooke I am not exactly sure. You can go into the uS range but I had better check with the Bitscope people about the exact details. I will forward this email. I am sure you will have an answer tomorrow. -Patrick Brooke Clarke wrote: Hi Patrick: They have an impressive line and I like PIC based products. Can you measure the period of a 1 PPS signal when the pulse width is on the order of 0 us? Have Fun, Brooke Clarke http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam Patrick wrote: ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi John I think I have the perfect suggestion for you. I spent 200+ hours researching scopes before I started my business, primarily because I am a cheap bastard. I finally found what I wanted, at the price I wanted. Please check out bitscope.com. I bought one over a year ago and it has paid for itself many times over. The support has been absolutely excellent. It is a PC controlled scope but it is external to the PC so it does not pick up noise.I bought the 310N, it has a built in logic analyzer, an signal out function and it can monitor two channels by multiplexing one. It can trigger from logic or analog. It runs on Windows and Linux. There are now Debian and Ubuntu packages for easy install and they are just releasing a control library. Together with my AEMC current probe I have used it to fix a number of difficult problems. I had to pay a 7% tariff to get it into Canada but shipping was cheap and the price is low to start with. I just checked the current price and it looks like it is $585 U.S Please don't hesitate ask if you have any questions. Bruce at Bitscope had been very helpful and sold me a great scope. I feel I owe him time considering the insane amount of questions I have asked him, of which none of them were due to shortcomings of his product. -Patrick ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Parallel voltage regulators
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi Tom I dont think you need the resistors these are current limited and the sense is inside the chip so the resistors dont do anything (you are thinking of a negative feedback effect). All that happens in paralled operation is that one may take the majority of the current til it current limits and the rest is provided by the other. They will need heat sinking. You can get Hi-power versions of these fixed regs as well or use one of them to drive a big transistor (the 2N2955 PNP used to be a popular choice up to 5A) for the series control. You may ned to lift the common leg with a diode to allow for the e-b drop on the pass transistor if you use an NPN. Cheers de Alan G3NYK - Original Message - From: Tom Clifton [EMAIL PROTECTED] To: time-nuts@febo.com Sent: Thursday, October 25, 2007 12:33 AM Subject: [time-nuts] Parallel voltage regulators A question for those that might know (or have an opinion)... I have in hand an LPRO rubidium reference that requires 1.7 amps at 24 volts while the oven warms, dropping to 500ma while it runs. Can I parallel three or four 7824 TO220 style 1 amp regulators with a quarter ohm half watt equalizing resistor on the output of each one? At maximum load there would be a quarter volt drop across the resistors and the LPRO is stated to be ok running on 16 to 32 volts. Tom __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Parallel voltage regulators
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Alan Melia wrote: Hi Tom I dont think you need the resistors these are current limited and the sense is inside the chip so the resistors dont do anything (you are thinking of a negative feedback effect). All that happens in paralled operation is that one may take the majority of the current til it current limits and the rest is provided by the other. They will need heat sinking. You can get Hi-power versions of these fixed regs as well or use one of them to drive a big transistor (the 2N2955 PNP used to be a popular choice up to 5A) for the series control. You may ned to lift the common leg with a diode to allow for the e-b drop on the pass transistor if you use an NPN. Nonsense look at the circuit. The base emitter drop of the pnp booster just increases the composite regulator dropout voltage. No diodes required to compensate Vbe drops. However this circuit is unreliable without current limiting of the PNP collector current. These days its simpler to use an LM338. Cheers de Alan G3NYK Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Parallel voltage regulators
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Magnus Danielson wrote: It is not that hard to acheive 2 A at 24 V after all. The old uA723 and variants would probably do the trick good enought for you with external transitor(s). I recommend to at least include fold-back for over-current protection, but adding an over-voltage in form of a crow-bar setup isn't too hard either. The point of the crow-bar is to cause fold-back and if that fails, blow the fuse, so include a fuse on the unregulated supply side. Cheers, Magnus Hej Magnus Using a 723 correctly configured with a low pass filter on the reference is a very low noise regulator solution with its output noise at least 20dB lower than that produced by a typical 3 terminal regulator. Most of the OEM open frame linear supplies use 723 regulators with external (to the 723) series pass transistors. These regulators have varying degrees of sophistication, some even use a zener plus emitter follower preregulator for the LM723. Some foolishly omit bleeder resistors across the reservoir capacitors which can lead to damage when making connections after powering the supply on and then off as the residual energy stored in the reservoir capacitors is more than sufficient to destroy the 723 should the output terminals be shorted. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Parallel voltage regulators
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Tom C, As Bruce notes below, the LM338K is a 5 amp job with a 35v max DC input rating. Just allow adequate heatsinking otherwise the 338 will foldback due to over temperature. There's plenty of on-line help to select the resistor values for 24 volts o/p. If you're really keen (?), add a few diodes with the mandatory bypass caps and you're cooking ! Cheers, Kit snip Hej Magnus Since the output voltage range of a 7824 is 23 - 25V that arrangement wont work very well unless you match all 7824's to within say 50mv or so of the same output voltage and mount them on a common heat sink. If you want to use a 3 terminal regulator why not just use an LM338 (plus a couple of resistors to set the output voltage) or similar device? Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY But he knows the period already to parts in 10e-9 or better. His email sez it's a PPS signal ex an Rb source. Not much point in trying to measure that with a scope timebase! So I still think he wanted to measure the ~10uS pulse width.. g DaveB, NZ - Original Message - From: Didier Juges [EMAIL PROTECTED] To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Wednesday, October 24, 2007 5:27 PM Subject: Re: [time-nuts] Scopes and 1 PPS signals? ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I read this: But using an HP 54501A DSO it's almost impossible to determine the period. http://www.prc68.com/I/O1814.shtml; It seems he wanted to measure the period. For once, the thread actually was about the original question :-) Didier -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dave Brown Sent: Tuesday, October 23, 2007 11:21 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Scopes and 1 PPS signals? I took Brookes original inquiry to be about measuring the width of the nominally 10 uS wide PPS pulse-in which case anything that alters the pulse width is a no-no. Precise and stable triggering delay to place one of the pulses in the on-screen area is all that is required. DaveB, NZ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.503 / Virus Database: 269.15.6/1086 - Release Date: 22/10/2007 19:57 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Parallel voltage regulators
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Tom Clifton [EMAIL PROTECTED] wrote: A question for those that might know (or have an opinion)... I have in hand an LPRO rubidium reference that requires 1.7 amps at 24 volts while the oven warms, dropping to 500ma while it runs. Can I parallel three or four 7824 TO220 style 1 amp regulators with a quarter ohm half watt equalizing resistor on the output of each one? At maximum load there would be a quarter volt drop across the resistors and the LPRO is stated to be ok running on 16 to 32 volts. Tom, Most of the oven circuits will tolerate a significant sag in potential during warm-up as long as the supply doesn't cut out. I've often run OCXO's and Rb's off a wimpy bench supply when my high current bench supply has been otherwise occupied. But if you want more current, the typical way to get a 3-terminal regulator to put out more than spec'ed is to place a big PNP power transistor across the input and output. You'll find the details in the datasheets of many parts (e.g. LM340). Also, check out the National AN-103 app note. It's old but it's still full of useful info. I refer you, at least for a laugh, to page 20 of Linear's AN-83: http://www.linear.com/pc/downloadDocument.do?id=4172 (Despite what others have posted, *some* 3-terminal regulators *can* be paralleled. The LT1083 can be -- checkout the datasheet -- but, nota bene, in the suggested circuit the ballast resistance is on the order of 0.01 ohms, not 0.25 ohms. But it isn't the best idea.) -ch ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi Dave: The problem is I don't have any documentation on the O-1814. The label does not say Frequency Standard or anything else about what it does. There is a very nice Rb source (M-100) inside and front panel connectors labeled 5 MHz In, 5 Mhz Out and 10 MHz Out so this may be a frequency standard. But it's not clear how any of the radios in the GRC-106 Pacer Speak system can take advantage of a reference frequency. http://www.prc68.com/I/PRC104.shtml#206 I'm beginning to think this is a Time Of Day standard. There are buttons for Rvc TOD and Send TOD as well as a lamp labeled Set Clock. I was looking for a serial clock stream that would be used to clock in the TOD serial data stream when I found the narrow pulse. I tried the SR620. It's bouncing around a 32 Hz period. My web host has changed the server that's hosting PRC68.com and I've sort of been distracted, but will try the diode pulse stretcher. If you look at the link above just below the GRC-206 system photo let me know if you see (new server) Starting with the top row: First VRC-83 Aircraft Radio - bold title (or the old server) GRC-206(V)1 can be fitted with Have Fun, Brooke Clarke http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam Dave Brown wrote: ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY But he knows the period already to parts in 10e-9 or better. His email sez it's a PPS signal ex an Rb source. Not much point in trying to measure that with a scope timebase! So I still think he wanted to measure the ~10uS pulse width.. g DaveB, NZ - Original Message - From: Didier Juges [EMAIL PROTECTED] To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Wednesday, October 24, 2007 5:27 PM Subject: Re: [time-nuts] Scopes and 1 PPS signals? ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I read this: But using an HP 54501A DSO it's almost impossible to determine the period. http://www.prc68.com/I/O1814.shtml; It seems he wanted to measure the period. For once, the thread actually was about the original question :-) Didier -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dave Brown Sent: Tuesday, October 23, 2007 11:21 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Scopes and 1 PPS signals? I took Brookes original inquiry to be about measuring the width of the nominally 10 uS wide PPS pulse-in which case anything that alters the pulse width is a no-no. Precise and stable triggering delay to place one of the pulses in the on-screen area is all that is required. DaveB, NZ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.503 / Virus Database: 269.15.6/1086 - Release Date: 22/10/2007 19:57 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Scopes and 1 PPS signals?
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY I tried the SR620. It's bouncing around a 32 Hz period. Brooke, You have a house standard, right? (GPSDO or cesium). Use your SR620 to take a set of N (10 or 100) TI measurements between your local reference and the O-1814 *rising edge*. Then again using the O-1814 *falling edge*. The difference between these two measurements is the average width of the O-1814 pulse. Easy to do very high accuracy. Check the sdev of each measurement to make sure nothing funny is going on; a couple of ns is OK. Hint: you get better data if you 1) sync the O-1814 1PPS to less than, say, 10 uS of UTC, and 2) if the O-1814 is tuned to within, say, 1e-11, of your house reference. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Parallel voltage regulators
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Thanks for all the good feedback! Looks like the LM388 is the way I'm to go. Got to toddle off to the local surplus shop in the morning to see what they have in the goodie bin. If they don't have it eBay is full of them. Tom __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Parallel voltage regulators
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY christopher hoover wrote: Tom, Most of the oven circuits will tolerate a significant sag in potential during warm-up as long as the supply doesn't cut out. I've often run OCXO's and Rb's off a wimpy bench supply when my high current bench supply has been otherwise occupied. But if you want more current, the typical way to get a 3-terminal regulator to put out more than spec'ed is to place a big PNP power transistor across the input and output. You'll find the details in the datasheets of many parts (e.g. LM340). Also, check out the National AN-103 app note. It's old but it's still full of useful info. I refer you, at least for a laugh, to page 20 of Linear's AN-83: http://www.linear.com/pc/downloadDocument.do?id=4172 (Despite what others have posted, *some* 3-terminal regulators *can* be paralleled. The LT1083 can be -- checkout the datasheet -- but, nota bene, in the suggested circuit the ballast resistance is on the order of 0.01 ohms, not 0.25 ohms. But it isn't the best idea.) -ch Tom The trouble with these circuits, as the designers will tell you, is that they were developed when the pnp power transistors had lower fts than their modern incarnations. Thus some engineering development is required to cure the oscillations that occur when a modern pnp with high ft is connected to boost the current output. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Parallel voltage regulators
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi Tom: When I had that problem a work around was to parallel a battery with the power supply (using a diode). The battery supplies the extra current while the oven warms up. If the power supply voltage is a little higher than the battery voltage when the oven is warmed up then the diode disconnects the battery. A resistor shunting the diode will then set a small charging current. Have Fun, Brooke Clarke http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam Tom Clifton wrote: Thanks for all the good feedback! Looks like the LM388 is the way I'm to go. Got to toddle off to the local surplus shop in the morning to see what they have in the goodie bin. If they don't have it eBay is full of them. Tom __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Parallel voltage regulators
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi Tom, If you really want to regulate the oven`s supply voltage, my National Voltage Regulator handbook shows that the LM317T will supply over 2 Amps, with an input/output differential of between 5, and 12.5 Volts. A single one of these should do the job OK. Cheers!,.Don Collie jnr. - Original Message - From: Tom Clifton [EMAIL PROTECTED] To: time-nuts@febo.com Sent: Thursday, October 25, 2007 12:33 PM Subject: [time-nuts] Parallel voltage regulators ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY A question for those that might know (or have an opinion)... I have in hand an LPRO rubidium reference that requires 1.7 amps at 24 volts while the oven warms, dropping to 500ma while it runs. Can I parallel three or four 7824 TO220 style 1 amp regulators with a quarter ohm half watt equalizing resistor on the output of each one? At maximum load there would be a quarter volt drop across the resistors and the LPRO is stated to be ok running on 16 to 32 volts. Tom __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Parallel voltage regulators
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Don Collie wrote: Hi Tom, If you really want to regulate the oven`s supply voltage, my National Voltage Regulator handbook shows that the LM317T will supply over 2 Amps, with an input/output differential of between 5, and 12.5 Volts. A single one of these should do the job OK. Cheers!,.Don Collie jnr. Never rely on typical specs always use the minimum spec which is 1.5A not quite enough. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] QCM
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi Ulrich, Ulrich Bangert wrote: Has anyone of you personal experience with QCMs (Quarz Crystal Microbalances) and give me a recommendation on a) what surface coating is suggested if the aim is to measure small amounts of humidity in clean air You should use gold coated QCM b) where such crystals may be supplied from in small quantities through my company (AXTAL - www.axtal.com) c) or if anyone is aware of a ready to go humidity sensor based on QCM technology There are several test systems on the market, but none of them is really low cost. Best regards Bernd Neubig __ AXTAL GmbH Co. KG Facility MOS Wasemweg 5 D-74821 Mosbach / Germany fon: +49 (6261) 939834 fax: +49 (6261) 939836 www.axtal.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Parallel voltage regulators
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Bollocs, Bruce! If National say it will do it, you can bet that it will. An LM338K will do the job too, but in my opinion it`s overkill, and in the event of a short circuit on the output of the regulator the current for the LM338 will only be limited to [...he gets the book..] 8 Amps [Typ], as against 2.2 Amp [Typ] for the LM317T. This would probably be too much for the transformer, rectifiers, and smoothing capacitor, effectively meaning that you would have no current limiting. If the input/output differential was kept in the range of 5 to 10 Volts, while the oven was stabilising, and the LM317 had an adequate heatsink, it would do the job nicely [and cheaper too!] Actually, it wouldn`t matter if the oven supply went unregulated while the temperature was stabilising, because you wouldn`t be using it for measurements during this time anyway - or is that a bit radical!? All the best!,..Don. - Original Message - From: Bruce Griffiths [EMAIL PROTECTED] To: Don Collie [EMAIL PROTECTED]; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Thursday, October 25, 2007 5:42 PM Subject: Re: [time-nuts] Parallel voltage regulators Don Collie wrote: Hi Tom, If you really want to regulate the oven`s supply voltage, my National Voltage Regulator handbook shows that the LM317T will supply over 2 Amps, with an input/output differential of between 5, and 12.5 Volts. A single one of these should do the job OK. Cheers!,.Don Collie jnr. Never rely on typical specs always use the minimum spec which is 1.5A not quite enough. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
