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solenoid controller

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Wp100

Well-Known Member
Hi,

A friend showed me this circuit which is designed to operate a model rail points solenoid which typically has 4ohm coils for use at typically 12-24vdc.
Its also acts as a CDU allowing an initial current burst when the switch is changed over and then decays to almost 0 ma while it is held on.

Have built and tested the circuit and it does work, though needing a quiet high voltage to produce a good movement from the solenoid.

The problem is that cannot quiet see How the circuit actually works ? :(

000229.jpg
 

Les Jones

Well-Known Member
Most Helpful Member
With the switch in the up position as shown in the schematic the lower capacitor is charged. (Via the resistor.) When the switch is moved to the lower position the lower capacitor is discharged though the lower coil. The top capacitor now gets charged via the resistor. When the switch is moved back to the upper position the upper capacitor is discharged through the upper coil.

Les.
 

large_ghostman

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I used to use these on my railway set. I switched over to servo's so I could get a slow authentic switching. Also I ditched the nail and drawing pin method of selecting points, to using cap touch sensing on a layout drawing. Then we moved to Scotland and I never unpacked the layout..........

One day I might. I have a massive layout I got given a few years ago, I guess I dont get time now, that and my interests have changed.
 

large_ghostman

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Pics I might have on mums laptop somwhere, drawings etc I can always redo. Works excellent and looks the Mutts Nuts
 

large_ghostman

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Wow that cost less than the micro I used! I forget which pic it was, alot of pics have cap touch now. It is well worth reading microchips app notes on the design side of the touch bit. Reading cap touch is easy, but good design of the button or slider needs some care, my speed control was slider touch. I also tried sil labs IR position control for speed. I will dig some links out, I know roughly where I have it all, and that is precisely why I am not rushing to grab it lol. Means I have to clear out my lab a bit to get to it :D.

But I will get the info for you when I have finished my jobs etc, might not be until weds. I have my finals (yet again), in 5 weeks. So much of my non down time is revising, I utterly went into melt down last year. Really stuffed my exams up with nerves, so this year I am going to smash them out the window!! I dont do well under exam pressure, I am fine with tests and other work, but sitting in a hall with a load of people just throws me totally.
 

Wp100

Well-Known Member
No worries, anytime will do, not in a rush.

Re the Exams, just be cool, why worry, its not going to change anything.

Use the old trick of relaxing , like with an interview, imagine the invigulators sat there in their underwear :D

Finals for ...?
 

large_ghostman

Well-Known Member
Most Helpful Member
No worries, anytime will do, not in a rush.

Re the Exams, just be cool, why worry, its not going to change anything.

Use the old trick of relaxing , like with an interview, imagine the invigulators sat there in their underwear :D

Finals for ...?
She was stunning last year, maybe thats where I went wrong, I should have left her underwear on :D:D
 
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