Hi folks, I'm onto the next bit of my linear clock / solenoid / stepper problem now... I have a circuit that pulses a solenoid once a second. This solenoid will eventually work with a wheel and spring and some pulleys and display the time in a linear fashion.
I'm driving the solenoid (6v) using one channel of a 2803A (darlington pair) IC and eventually want the whole thing to be regulated by the time-keeping chip from a quartz clock. This is the little pcb from the clock, that appears to emits a 1.3v pulse, about 30ms long every second. It usually sends the pulse into a motor coil to turn a gear. It goes slightly negative (0.1v) as well as positive. I wonder if this is something to do with it expecting to be driving an inductor/charging a cap or something.
Now, I've used the blue portion of the circuit in my drawing (attached) successfully: I generate a 5v pulse every second from an arduino. The solenoid actuates and everyone's happy.
**broken link removed**
**broken link removed**
The 1.3v from the quartz movement isn't enough to trigger the 2803 though it seems, so I read up and decided I need a comparator to fire a pulse whenever there was a voltage from the quartz chip outputs. Don't have a comparator, but read that I could use an opamp as one... Constructed circuit B (red circuit) with no result. I did notice that I did get movement when I connected one of the quartz chip output to the same ground as the opamp though, but it was inverted. That is, the solenoid was on for most of the time, but briefly pulsed off every second. Ha, says I, maybe I can use the other op amp on the TL082 as an inverter (that should be possible I think?), but as I rewired it I noticed that the output of the second opamp was behaving the same the output of the first one - even though it had no inputs wired up. (circuit c - purple).
So that made me pause and wonder if it was something to do with the power to the TL082 that was making this behaviour. Was my circuit doing something funky to ground.
Anyway, at that point my rudimentary electronics knowledge was all used up, and I thought I'd better ask someone who knows something.. Ie you guys.
Any ideas for what's happening here, or what I _should_ be doing? Hope someone can give me a hand here!
Thanks
Sandy Noble
I'm driving the solenoid (6v) using one channel of a 2803A (darlington pair) IC and eventually want the whole thing to be regulated by the time-keeping chip from a quartz clock. This is the little pcb from the clock, that appears to emits a 1.3v pulse, about 30ms long every second. It usually sends the pulse into a motor coil to turn a gear. It goes slightly negative (0.1v) as well as positive. I wonder if this is something to do with it expecting to be driving an inductor/charging a cap or something.
Now, I've used the blue portion of the circuit in my drawing (attached) successfully: I generate a 5v pulse every second from an arduino. The solenoid actuates and everyone's happy.
**broken link removed**
**broken link removed**
The 1.3v from the quartz movement isn't enough to trigger the 2803 though it seems, so I read up and decided I need a comparator to fire a pulse whenever there was a voltage from the quartz chip outputs. Don't have a comparator, but read that I could use an opamp as one... Constructed circuit B (red circuit) with no result. I did notice that I did get movement when I connected one of the quartz chip output to the same ground as the opamp though, but it was inverted. That is, the solenoid was on for most of the time, but briefly pulsed off every second. Ha, says I, maybe I can use the other op amp on the TL082 as an inverter (that should be possible I think?), but as I rewired it I noticed that the output of the second opamp was behaving the same the output of the first one - even though it had no inputs wired up. (circuit c - purple).
So that made me pause and wonder if it was something to do with the power to the TL082 that was making this behaviour. Was my circuit doing something funky to ground.
Anyway, at that point my rudimentary electronics knowledge was all used up, and I thought I'd better ask someone who knows something.. Ie you guys.
Any ideas for what's happening here, or what I _should_ be doing? Hope someone can give me a hand here!
Thanks
Sandy Noble
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