Have you looked into the details of TVSs? My understanding is that they suffer a little damage every time they absorb a transient to protect something else, and they can only do is so many times before they need replacement, unlike zener diodes which have no limit to life as long as they're not ...

I will make another perf board with some stak-ons (have a lot of board mount ones) and the TVS diodes. Diodes? As your TVS diode is bidirectional it will serve to replace both of the zeners in the diagram I posted. So, you just need a single 43V TVS diode. (You could put 2 or more identical TVS's ...

Funny thing, every motor and pump belongs to a car! Yes, I should've remembered that before assuming the drive motor ran on 115VAC!
and some 1v5KE51CA (43v ish breakdown and bidirectional). Would either of those TVS Diodes work in place of 2 watt zener? A 43 ish bidirectional TVS sounds good to me ...

Not going to be easy to break in anywhere other than the motor wires. Yes, I was afraid of that. But the good news is, I was mistakenly assuming the motor was powered by the AC Mains -- 115V or whatever. Hence my remark about opto-couplers. Low voltage DC will be a lot easier to deal with -- we can ...

Here is the flip flop with debounce that Jeff showed me how to make.
It works! And depending on when you activate it, very interesting things happen.
As surmised it doesn’t turn the motor off but it does stop the clock...sort of.
When you resume, it resets to the stating point of that particular ...

The rotation motor is fed from the power supply board and not marked in a way that would make sense to me.
Its simple, just a TIP140, couple of op amps and a relay to select from a 3 different voltages for the speed. I suspect the parts that look like op amps are actually optocouplers, used to ...

I could add a switch to interrupt power to the motor. Yup. Just be aware that interrupting power to an inductive load results in voltage spikes that can be large enough to be destructive. Because the relay interrupts power the machine probably has some sort of protection network to deal with this ...

Its simple, just a TIP140, couple of op amps and a relay to select from a 3 different voltages for the speed. I think you can expect the relay status to remain unchanged when the CPU is stopped. Thus, an experiment seems unnecessary. But by all means go ahead if that's your inclination!

-- Jeff ...

PS- Photoman, I'm curious about your remark here. Can you elaborate? This is all to see if it will actually turn the motor off so I can grab the film and run an off board process.
Also: BDD may have a point in regard to the following. For example, interrupts generated by the 6522 VIAs won't get ...

The motor is a DC motor and I kid you not its actually a windshield wiper motor from a BMW.
I don't know if its luck or just a great motor but its lasted over 20 years. Probably 10 times the use it would get in a car.
Speed is controlled by a Hall effect sensor and run off an H bridge.
The entire ...

Speed is controlled by a Hall effect sensor and run off an H bridge. Hmm, and the motor is reversible, is that right? And is it the 65C02 that turns the H Bridge on and off? If so, then stopping the CPU will probably result in the motor going to zero or to 100%.

Probably in normal operation it ...

I found the TI CD74HC4066E‎ or even better the HCT CD74HCT4066E. Those look like they have enough bandwidth.
Ill also pickup a few of floobydust's MXO45HST-3C-1M000000‎ 1mhz oscillators with an enable pin.
I can try both ways.
I'd say your easiest option is to simply pull the RDY pin low. As noted ...

I found the TI CD74HC4066E‎ or even better the HCT CD74HCT4066E. Those look like they have enough bandwidth.
Ill also pickup a few of floobydust's MXO45HST-3C-1M000000‎ 1mhz oscillators with an enable pin.
I can try both ways. I can just cut the power to the machine if it decides it wants to fly off ...

Hi Garth,

Thanks for all of your help!
The processor is timed so it needs the accuracy of the crystal oscillator.
My first thought is a 4016 or a 4066 analog/digital switch.
Input/Output 1 is the clock taken from the oscillator to the R65C02 Phi0.
I was also thinking since I need to hold the clock ...

The Rockwell R65C02's can be stopped with phase 2 high. I've done it several times, to single-cycle it for tests. Regardless of which way you go, you'll have to make sure you don't have glitches or runt pulses. (I wouldn't call the WDC one a "variant" though, since WDC designed the 65C02.)
Thanks ...