I have an open collector toggle signal, instead of get on/off at 24
volts and grnd, I would like to get -12v to +12v, I am not an
electronics guy but with a little knowledge in the field, could anyone
tell me how to do this? Great thanks in advance for any posts..
Hi, Gary. The first thing you're going to have to do is get +12V and
-12V supplies. You can get the +12V from the +24V with an LM7812, a
positive 12V regulator, like this (view in fixed font or M$ Notepad):
| ____
| +24V | | +12V
| o----o----|7812|----o-----o
| | |____| +|
| --- | ---
| --- | ---
| .1uF| | 10uF|
| | | |
| o----o------o-------o-----o
| GND
(created by AACircuit v1.28.6 beta 04/19/05
www.tech-chat.de)
Now for the negative voltage, you can use a 555 as a voltage inverter
like this:
|
| +12V +12V +12V
| | + +
| .-. | |
| | |24K .---o----o---. C = 100uF 25V
| | | | 8 4 | D = 1N4002
| '-' | | C
| | | |
| o-----o7 | +|| D -11.3V
| | | 3o---||--o----|<--o----o
| .-. | | || | |
| | |56K | 555 | V C ---
| | | .--o6 | D - ---
| '-' | | | | +|
| | | | | | |
| o--o--o2 | === ===
| | | | GND GND
| --- | 1 5 |
| --- '---o----o---'
| | 3.3nF |
| === ===
| GND GND
|(created by AACircuit v1.28.6 beta 04/19/05
www.tech-chat.de)
As long as you don't need more than 20mA or so from your negative
supply, this will work pretty well. Feel free to post again if an
unregulated 11.3V doesn't do it.
You're almost there. Now, if you can live with 0V in = +12V out and
24V in = -12V out, a simple transistor will do the job, like this:
|
| +12V +12V
| | |
| .-. |
| 10K| | |
| | | |
| 1N4002 '-' |
| Vin ___ | |<
| o-|<--|___|-o-| 2N3906
| 10K |\
| +24V/0V |
| o
| |
| .-.
| 2.2K 1/2W| |
| | |
| '-'
| |
| -11.3V
(created by AACircuit v1.28.6 beta 04/19/05
www.tech-chat.de)
Now that you've got one possible answer, how about posting again and
describing why this one won't work? If this is too complicated for
your skill level, there are simpler (and more expensive) solutions, I
suppose. Any additional information about your application would also
be helpful -- we might see a roadblock you don't.
Cheers
Chris