The 5 volt CAS signal from the TM-V7 can very easily be converted to an 8 volt (or even higher) level by using a VP0300L switching MOSFET and pullup resistor of about 510 ohms to your 8 volt source. If logic level conversion is required, then use the VN0300L or 2N7000 MOSFET. They are available from JDR Micro Devices.
If you are not familiar with these devices, they are WONDERFUL switching devices and require almost no drive current on the gate (unlike a 2N2222 or 2N3904), so you can apply 5 volt logic levels to them directly to drive relays directly if you need to. I've used bunches of these for various tasks within our repeater systems and personal radio projects. Ron WW8RR -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Joe Montierth Sent: Tuesday, May 03, 2005 7:52 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] I need to take 5 volts to 8 volts, and one have a schematic --- w9mwq <[EMAIL PROTECTED]> wrote: > Wonder if anyone has a simple diagram to build a > small circuit from 5 > volts to about 8 volts. Was told I could use an > opto isolator, but am > not familiar with them. I'm getting ready to > interface the Kenwood TM- > V7 radios to the RVS-8 voter, am told it needs at > least 8 volts to run > it. The TM-V7a I know has 5 volts out of the packet > controller > connection. I will also need to take a 3 volt up to > 8 volts from my > GE receiver. Any suggestions. Thanks. > > Mathew > > What you are needing is "level translation" of digital levels from one voltage to another. You can do it with transistors and resistors, op-amps, or other chips designed to do this. Depending on how many receivers you need to do will determine the actual easiest and cheapest solution. I did a similiar thing with an RVS-8, and used 2 LM324 op-amps to do the level shifting. Besides the 2 chips, a few resistors were required. I built the whole thing on a RS proto board. Or you could use a ULN2003 or similiar chip. Another solution is to run a 47K pullup from the RVS-8 input to 12v, and a series zener diode of about 3.9 volts to the RX COR out. This will change your 0 to 5 volt logic to 3.9 to 8.9 volt logic, which is enough to make the RVS unit work. Joe __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Yahoo! Groups Links Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
