Allow me to explain..
I have on going project, that does not involve a Propeller or Stamp, so I did not what to put this thread on those forums. So...., I have built a few stand on golf carts, to carry me and clubs around the golf course. I use 24 volt power chair motors from Ebay, design my on PWM and gate drivers, using 24 volts. Carts use front wheel steering, with handle bars, like a bicycle.
Now, I thought I would try a joystick application, to avoid the making from scratch, the front wheel steering (aka rack and pinnon jchain drive). Instead by using the drive motors to steer left, right and reverse. And using large type of casters for the front wheels. So, I went on line and found a joystick circuit that I built and designed
for a PCB . This circuit is called "Dual Channel Interface Board", from a company in England, called 4QD dated 14 April 2000, Issue 5. You can google that and see the circuit if you look around for it..and I have emailed with them, and there is no problem in me using that circuit...design.
As I said, the joystick circuit works very well, but...ya, here is the but...it operates on 9.1 volts, so the output for speed on both outputs will only approach 7 volts, and I need an output from 0 volts, at standstill to 16 volts, full speed to gate drive my very high amp, MOSFETS. Right now, I am using a handlebar twist drive throttle (a variable hand gripe potentiometer..5K) to the threshold pin 5 of a 555 to develop the necessary PWM, which in turns drive a HCPL3120, one for each wheel.
If I try to run the 555 on the 7 volts I do not get full speed...and I have tried to increase the voltage running the Duel Channel circuit, but that causes the circuit to no longer give me any output in "reverse joystick". Some sort of imbalance in that Duel Channel circuit op amps, I believe.
With everyone's vast knowledge, would anyone know of a..lets call it a "variable DC to DC driver/amplifer circuit, that would take a variable DC voltage of 0 to 7 volts and give me a corresponding variable DC voltage of 0 to 16 volts out?
I could send you some photos of what I am working on and doing, if I knew where to send them. Please understand that this is just a hobby for me....sort of reinventing the wheel....but it is fun. Especially, on the golf course, others ask, where did you get that, that is cool, and I get to say, well I made it....!
BTW, the 555 runs on 16 volts, which does give me the necessary PWM at a set frequency of around 10Khz. The higher frequency to avoid motor scream noise due to the PWM. Anyways, the HCPL3120 is a 2.5 Amp Output Current IGBT Gate Drive Optocoupler. I am using it to drive two TrenchGate Power MOSFET IXFN360N10T, one for each motor/gearbox which will handle 360 amps, but my motors do not draw that much...up hill with me on, around 50 amps...each. I did design the snubber circuits, and the forward/reverse/electric park brake, when the cart stops moving to lock the wheel, until throttle is once again applied....
I do not have alot of savy with op amps. The circuit that I built for the joystick came from someone else, as I mentioned above. I would appreciate some accurate detail information or even a circuit that possible you/someone has designed and used.
I will keep looking around, and thanks for your time...Dennis