Hello, this is my first post on the forum. I am very much a novice in electronics but willing to learn. I'm working on a project to use a standard R/C system to control certain functions of a piece of power equipment that uses 12vdc motors. I'm feeding the PWM signals from each channel of the R/C Rx to a low-pass filter, then to an op-amp, and then to a window comparator that gives me two outputs to control an h-bridge. I need some help with the h-bridge. The existing speed control PCB for the FWD/REV uses a PWM +12VDC signal to the (-) side of the motor to control the speed in FWD only. The further you turn the speed control pot, the longer the negative going pulses of the PWM signal are. REV is full speed.
I think I need to invert this signal (SPEED_PWM) and connect it to the gate low-side N-channel FET? Is there a way to configure an LM339 comparator as an inverter? Is there a better device to do this? I will be ordering more parts.
When both A and B inputs to the h-bridge are OFF (HIGH), is appears that there may be an issue with SPEED_PWM being directly connected to Q4? Maybe I need to have an ENABLE signal for this. Any suggestions on a better way to do this? I can reconfigure the window comparator for ON= HIGH outputs if it would help.
I would appreciate any advice on the overall circuit, especially in regards to any missing capacitors and diodes. Vss is from a 12v battery being charged by an alternator, hence the 12-14.5vdc notation.
I think I need to invert this signal (SPEED_PWM) and connect it to the gate low-side N-channel FET? Is there a way to configure an LM339 comparator as an inverter? Is there a better device to do this? I will be ordering more parts.
When both A and B inputs to the h-bridge are OFF (HIGH), is appears that there may be an issue with SPEED_PWM being directly connected to Q4? Maybe I need to have an ENABLE signal for this. Any suggestions on a better way to do this? I can reconfigure the window comparator for ON= HIGH outputs if it would help.
I would appreciate any advice on the overall circuit, especially in regards to any missing capacitors and diodes. Vss is from a 12v battery being charged by an alternator, hence the 12-14.5vdc notation.
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