Hi all,
I am a hack trying to finish up a project, and could use some help I need to debounce a positive signal from a SPST tactile switch to a PWM relay. The signal (and VCC) is 12VDC, and the relay will close with anything above ~2VDC. In its NO state, any quiescent signal below 2V is fine and will not close the circuit. The switch, when closed, feeds VCC to the relay's input trigger.
Below is the SPST circuit as I had planned it. I had originally spec'd a MAX6816EUS (MAX6816EUS datasheet) to handle debouncing:
Unfortunately, my real world experience has been that the MAX6816's input appears to be pulled high internally, and as a result my relay sees a signal (and activates!) when no signal should be present. I have not been able to get the MAX6816EUS to work in my circuit. I am tired of banging my head against this wall and want to move on to a different approach. (And if anyone knows what I'm doing wrong with the MAX6816EUS, I'm all ears. I just want to solve this debouncing problem and move on.)
It looks like there are a lot of options for a hardware debounce circuit, but most are designed to debounce a switch that carries a ground signal. I am trying to debounce a positive signal, so it seems like a lot of the designs I am seeing won't work for my circuit. I could use some help.
It looks like an RC circuit similar to this one that could work for me if I knew the right values for D1, R1, R2, and C1:
I would be very grateful if someone could provide some ballpark values (and a diode recommendation) to allow me to use the above RC circuit as a debounce solution for my project.
Honestly, though, I am open to any compact debounce circuit that will work for a SPST switch carrying a positive signal. The switch will remain pressed/closed for 5-10 seconds at a time, so the initial delay can be several hundred ms, if necessary - it really doesn't matter, the user will keep the button pressed until the task is complete. I just need to debounce the initial press of this button.
Thanks for any help or light you can shed on this!
I am a hack trying to finish up a project, and could use some help I need to debounce a positive signal from a SPST tactile switch to a PWM relay. The signal (and VCC) is 12VDC, and the relay will close with anything above ~2VDC. In its NO state, any quiescent signal below 2V is fine and will not close the circuit. The switch, when closed, feeds VCC to the relay's input trigger.
Below is the SPST circuit as I had planned it. I had originally spec'd a MAX6816EUS (MAX6816EUS datasheet) to handle debouncing:
Unfortunately, my real world experience has been that the MAX6816's input appears to be pulled high internally, and as a result my relay sees a signal (and activates!) when no signal should be present. I have not been able to get the MAX6816EUS to work in my circuit. I am tired of banging my head against this wall and want to move on to a different approach. (And if anyone knows what I'm doing wrong with the MAX6816EUS, I'm all ears. I just want to solve this debouncing problem and move on.)
It looks like there are a lot of options for a hardware debounce circuit, but most are designed to debounce a switch that carries a ground signal. I am trying to debounce a positive signal, so it seems like a lot of the designs I am seeing won't work for my circuit. I could use some help.
It looks like an RC circuit similar to this one that could work for me if I knew the right values for D1, R1, R2, and C1:
I would be very grateful if someone could provide some ballpark values (and a diode recommendation) to allow me to use the above RC circuit as a debounce solution for my project.
Honestly, though, I am open to any compact debounce circuit that will work for a SPST switch carrying a positive signal. The switch will remain pressed/closed for 5-10 seconds at a time, so the initial delay can be several hundred ms, if necessary - it really doesn't matter, the user will keep the button pressed until the task is complete. I just need to debounce the initial press of this button.
Thanks for any help or light you can shed on this!