HIGH-RATE SPEED CONTROL by Keith Walker I decided to use it and the control swith unit, to build a forward/reverse speed control on a small boat, using two radio channels. I made some changes to the original design to have a better control over trottle speed. I am using a Futaba radio, 6 Ni-Cd cells and a motor normally used for 1:10 car models.
Here are my changes:
* Eliminate VR1, R13 changed to the value of 33 k-ohm and C3
changed to 0.2 uf. This allows me to use VR1 for another purpose.
* VR1 now used (with an added 1k resistor) to pull up the high
rate wave, to better fit the radio signal output from IC1A.
* I use an IRFZ44 MOSFET, that was easier for me to find.
Here are the changes I made to the pcb. (4 KB GIF file), and component placement.
To set up trimmers you have to set VR2 in middle position and VR1 to start position (0 ohm). Then move radio transmitter to throttle off (all down for me), turn VR1 till trottle start moving and then a little back. Now adjust VR2 to have full trottle and proportional driving. The trimmers are still interactive so after each VR2 setting VR1 adjusting may be required.
(Now it works but but could be better. As soon as I have time I'll work on it. I'll adjust R8, R9, R13, C3 and the added resistor. I think that to have a better proportional control over the motor speed, it must drive the motor quickly from 0 to about 1/3 of the battery voltage and then proportionally to full speed.)
And from a subsequent message:
I ended the job using the following components values:
* R9 6.8 K
* R8 12 K
* C3 0.2 micro
* added resist. 4.7 K
