Software Support > Automated Projects
Using parallel port and mamehooker for gun recoils
charlieram:
Hi, Me agian. I have been thinking about an isolated circuit and I came across this on my travels.
V+ (12V)
|
+------------+-----+------+
| | |
Parallel | | |
Port | D1 --- |
| 1N4001 / \ Relay coil
R1 1 ----------- 5 | /---\ |
D(x) ----1k------| Opto- |-----+ | |
| Isolator | +-----+------+
GND -------------| |-+ | |
2 ----------- 4| | |
CNY 17 or | R2 | / |
4N25 | 4.7K B |/ C T1 |
+--\/\/\/\/---| BC547A |
| |\ E |
| | V | /
/ | B |/C T2
\ R3 +----------| power
/ 10 kohm |\E transistor
\ | v
| |
+----------------------------+
|
external circuit ground
So I have more questions! Would I be able to power this directly using my 24v 5A PSU without changing anything else, I would be using the same Mosfet as before and I have come across some cheap Opto Isolators, I would be grateful if you could check over the following circuit and let me know what you think, would I need a lower voltage supplying the gate of the Mosfet? (I did read about using a 7805 voltage regulator but the generate a lot of heat)
Cheers.
DaOld Man:
Thats looks like it would work, but the opto isolator circuit can be made a lot simplier.
Check out this drawing.
With Pin4 high, the leds on the optos will not light, causing the opto ouput to be off regardless of pin 2 or pin3 being high or low.
But if Pin 4 is low, it supplies a ground to each opto, so that they can be turned on or off by pin2 2 or 3 respectively.
(Im at work and spell check dont work here, so please disregard any misp[laced key punches.)
charlieram:
That definitely looks a more elegant solution thanks, I was looking over the specs of the mosfet which I chose based on the Aimtrak recoil module, but if I'm reading it right then it wont be able to cope with the 24v input on the gate so i started searching for one more suitable (with my limited knowledge!).
I found this one on RS online FQPF10N20C, I've attached the datasheet so if you could take a quick look and let me know If i am right in thinking this would work or at least handle the 24v supply I would be very grateful, This sure is a very steep learning curve.
Also I don't know why but It feels like were having private conversation in public view!
DaOld Man:
That RS mosfet looks to me like it will work.
I would breadboard your circuit first, just to make sure everything works like you want. I hate to solder stuff up then find out a different sized resistor (etc) was needed or would make it work better.
Posting your questions for everyone to read is a lot better, IMO, than messaging, because someone else could benefit from it and there are others on here that can double check my suggestions.
After reading that spec sheet, it looks like that mosfet would be a good transistor to use for our home made H Bridge motor drivers too. So see, your questions and ideas are already starting to benefit others.
charlieram:
Glad to be of help ;D
Anyway, after some more studying ??? and a £4.95 delivery charge from RS Components I decided to check out CPC Farnell, Some components weren't available there and the opto isolator I previously picked wasn't suitable (I think) so this is what I have gone for and placed the order so fingers crossed my next post will contain some real pictures and not just drawings!
Here is my final schematic with the actual components I ordered.
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