[Repeater-Builder] Micor COS issues.... continuing
I've been fighting this issue for a while now. I've tried some bandaids to deal with it, tried multiple repeater controllers (including one I designed myself with an ATMEGA328 Microcontroller (I'll probably be releasing this design as open source coming up)... and I'm fighting the same problem everywhere... My micor COS signal is weird. When the squelch is closed, I get right around 8 volts, taken from pin 8 of the modified mobile audio/squelch board - the tried and true process just about everybody uses. When the squelch opens, I'm at not ground potential, but right about half a volt. This isnt really the sort of logic signal I want (I want this thing to be dead nuts zero, not half a volt). What is the deal here? I've tried adding resistors in series to fudge things and cause voltage drop, but thats not really even working that well. I've tried the 2n circuit, but that doesnt really have a lot to do with this (although a variation of that might come into play I suspect) How do I best solve this so I can get my repeater on the air?? This is very close to the last issue I have remaining to solve. Help / advice is greatly appreciated. Josh
Re: [Repeater-Builder] Micor COS issues.... continuing
Hi Josh, Instead of resistors, try diodes in series. Each Diode will drop your voltage. I have series a couple to get rid of standing voltage, especially if you are down to a half volt or so. 73 JIM On Mon, Jun 21, 2010 at 11:57 AM, Josh josh.kit...@gmail.com wrote: I've been fighting this issue for a while now. I've tried some bandaids to deal with it, tried multiple repeater controllers (including one I designed myself with an ATMEGA328 Microcontroller (I'll probably be releasing this design as open source coming up)... and I'm fighting the same problem everywhere... My micor COS signal is weird. When the squelch is closed, I get right around 8 volts, taken from pin 8 of the modified mobile audio/squelch board - the tried and true process just about everybody uses. When the squelch opens, I'm at not ground potential, but right about half a volt. This isnt really the sort of logic signal I want (I want this thing to be dead nuts zero, not half a volt). What is the deal here? I've tried adding resistors in series to fudge things and cause voltage drop, but thats not really even working that well. I've tried the 2n circuit, but that doesnt really have a lot to do with this (although a variation of that might come into play I suspect) How do I best solve this so I can get my repeater on the air?? This is very close to the last issue I have remaining to solve. Help / advice is greatly appreciated. Josh -- Jim Cicirello 181 Stevens Street Wellsville, N.Y. 14895 (585)593-4655
Re: [Repeater-Builder] Micor COS issues.... continuing
At 08:57 AM 6/21/2010, Josh wrote: When the squelch is closed, I get right around 8 volts, taken from pin 8 of the modified mobile audio/squelch board - the tried and true process just about everybody uses. When the squelch opens, I'm at not ground potential, but right about half a volt. This isnt really the sort of logic signal I want (I want this thing to be dead nuts zero, not half a volt). \ -That output is an open collector bipolar device, so the best you can hope for is .6 volts above ground. This may not be enough for what you're driving. I've done many MICOR mods for external controllers and I've always simply used a simple NPN small signal transistor (2N or 2N3904) as a buffer. Of course this inverts the COS signal (which is just fine with me as I've never liked active low COS signals). 1 transistor and 2 resistors is all it takes Ken -- President and CTO - Arcom Communications Makers of repeater controllers and accessories. http://www.arcomcontrollers.com/ Authorized Dealers for Kenwood and Telewave and we offer complete repeater packages! AH6LE/R - IRLP Node 3000 http://www.irlp.net We don't just make 'em. We use 'em!
RE: [Repeater-Builder] Micor COS issues.... continuing
Josh; You could also use a 2n7000 fet in place of the 2n device in that circuit.. 2n700 FET's have an on trigger of between 2-4 volts. as the switch point and switch like an npn transistor for this app.. the input does not require a resistor ( the gate )as it can swing to ~12v before destruction becomes an issue. you can limit it if you want but the gate resistance is in the meg ohm region. it is all but a dc switch for this application. I had 2 Spectras converted to a repeater I was working on last week and had the same issue of about .8 volt to 8. I put a silicon rectifier 1n4002 type diode in series, anode to the cor of the station, cathode to the controller and then put a pull down-to-ground resistor on the cathode end to really hard pull to ground.. about 1k or so.. switching at that point became effectively zero to 8v. My controller was happy Doug KD8B From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of James Cicirello Sent: Monday, June 21, 2010 12:43 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Micor COS issues continuing Hi Josh, Instead of resistors, try diodes in series. Each Diode will drop your voltage. I have series a couple to get rid of standing voltage, especially if you are down to a half volt or so. 73 JIM On Mon, Jun 21, 2010 at 11:57 AM, Josh josh.kit...@gmail.com wrote: I've been fighting this issue for a while now. I've tried some bandaids to deal with it, tried multiple repeater controllers (including one I designed myself with an ATMEGA328 Microcontroller (I'll probably be releasing this design as open source coming up)... and I'm fighting the same problem everywhere... My micor COS signal is weird. When the squelch is closed, I get right around 8 volts, taken from pin 8 of the modified mobile audio/squelch board - the tried and true process just about everybody uses. When the squelch opens, I'm at not ground potential, but right about half a volt. This isnt really the sort of logic signal I want (I want this thing to be dead nuts zero, not half a volt). What is the deal here? I've tried adding resistors in series to fudge things and cause voltage drop, but thats not really even working that well. I've tried the 2n circuit, but that doesnt really have a lot to do with this (although a variation of that might come into play I suspect) How do I best solve this so I can get my repeater on the air?? This is very close to the last issue I have remaining to solve. Help / advice is greatly appreciated. Josh -- Jim Cicirello 181 Stevens Street Wellsville, N.Y. 14895 (585)593-4655
RE: [Repeater-Builder] Micor COS issues.... continuing
I always use an NPN transistor (2N4401 or whatever floats your boat) as an inverter on the Micor COR, with a voltage divider on the base. Micor COR to base through 10K, 4.7K from base to emitter, ground emitter, collector becomes active-high COR. Pull up collector with 12V through 1K (or whatever) if your controller doesn't have a pull-up internally. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Josh Sent: Monday, June 21, 2010 11:58 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Micor COS issues continuing I've been fighting this issue for a while now. I've tried some bandaids to deal with it, tried multiple repeater controllers (including one I designed myself with an ATMEGA328 Microcontroller (I'll probably be releasing this design as open source coming up)... and I'm fighting the same problem everywhere... My micor COS signal is weird. When the squelch is closed, I get right around 8 volts, taken from pin 8 of the modified mobile audio/squelch board - the tried and true process just about everybody uses. When the squelch opens, I'm at not ground potential, but right about half a volt. This isnt really the sort of logic signal I want (I want this thing to be dead nuts zero, not half a volt). What is the deal here? I've tried adding resistors in series to fudge things and cause voltage drop, but thats not really even working that well. I've tried the 2n circuit, but that doesnt really have a lot to do with this (although a variation of that might come into play I suspect) How do I best solve this so I can get my repeater on the air?? This is very close to the last issue I have remaining to solve. Help / advice is greatly appreciated. Josh
Re: [Repeater-Builder] Micor COS issues.... continuing
Hi Josh, You can mod your Micor, but you'll keep running into similar problems when you interface your controller with other repeaters. COR outputs can be driven by Darlington transistors, LED drivers, squelch ICs, etc., and not all will go as low as you want. Here's how we've designed our controllers' COR, CTCSS, and logic inputs for many years: Feed the COR signal to the top of a voltage divider. The upper resistor is 10K and the lower is 4.7K. Feed the junction of the divider to the base of an NPN such as a 2N3904, 2N, etc. You'll have a 3:1 voltage divider that in essence multiplies the transistor's base-emitter drop by three, so the input threshold will be ~2V instead of ~0.7V. And, you'll have 10K and an NPN to buffer the outside world from whatever logic IC you're using for your input port. If you want a pullup resistor, tie a 4.7K from the top of the divider to +5V. You'll find this circuit in all our schematics at www.scomcontrollers.com. 73, Bob Bob Schmid, WA9FBO, Member S-COM, LLC PO Box 1546 LaPorte, CO 80535-1546 970-416-6505 phone 970-419-3222 fax www.scomcontrollers.com -Original Message- From: Josh josh.kit...@gmail.com To: Repeater-Builder@yahoogroups.com Sent: Mon, Jun 21, 2010 9:57 am Subject: [Repeater-Builder] Micor COS issues continuing I've been fighting this issue for a while now. I've tried some bandaids to deal with it, tried multiple repeater controllers (including one I designed myself with an ATMEGA328 Microcontroller (I'll probably be releasing this design as open source coming up)... and I'm fighting the same problem everywhere... My micor COS signal is weird. When the squelch is closed, I get right around 8 volts, taken from pin 8 of the modified mobile audio/squelch board - the tried and true process just about everybody uses. When the squelch opens, I'm at not ground potential, but right about half a volt. This isnt really the sort of logic signal I want (I want this thing to be dead nuts zero, not half a volt). What is the deal here? I've tried adding resistors in series to fudge things and cause voltage drop, but thats not really even working that well. I've tried the 2n circuit, but that doesnt really have a lot to do with this (although a variation of that might come into play I suspect) How do I best solve this so I can get my repeater on the air?? This is very close to the last issue I have remaining to solve. Help / advice is greatly appreciated. Josh
RE: [Repeater-Builder] Micor COS issues.... continuing
Here's how we've designed our controllers' COR, CTCSS, and logic inputs for many years: Feed the COR signal to the top of a voltage divider. The upper resistor is 10K and the lower is 4.7K. Feed the junction of the divider to the base of an NPN such as a 2N3904, 2N, etc. You'll have a 3:1 voltage divider that in essence multiplies the transistor's base-emitter drop by three, so the input threshold will be ~2V instead of ~0.7V. And, you'll have 10K and an NPN to buffer the outside world from whatever logic IC you're using for your input port. Seems that sick minds think alike, Bob :-)
Re: [Repeater-Builder] Micor COS issues.... continuing
Hi Jeff, Here's how we've designed our controllers' COR, CTCSS, and logic inputs for many years: Feed the COR signal to the top of a voltage divider. The upper resistor is 10K and the lower is 4.7K. Feed the junction of the divider to the base of an NPN such as a 2N3904, 2N, etc. You'll have a 3:1 voltage divider that in essence multiplies the transistor's base-emitter drop by three, so the input threshold will be ~2V instead of ~0.7V. And, you'll have 10K and an NPN to buffer the outside world from whatever logic IC you're using for your input port. Seems that sick minds think alike, Bob :-) I'm in good company, then... :-) Bob
