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Relay switcher

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Mike_2545

Super Moderator
Ok, about 3 weeks ago my hard drive crashed and I was out of service for awhile. So I decided to make a bench power supply. I had all of the ingredients,
  • Transformers
  • Positive and negative voltage regulators
  • Capacitors
  • Kick ass retro cabinet
  • Digital volt meter

Problem is I only had the one volt meter, so I settled on a three way rotary switch to go switch between the positive and negative sides. With a twist for the middle position.

I wanted to make a switcher that would switch back and fourth between the two voltage values, like the relay ct: (below)

I thought slamming back and fourth with a regular flip flop would be a bit harsh on the digital meter, maybe I just wanted to be different.

Now I'm absolutely positive I went about this the long way round, but this is what I came up with; and for just a hobbiest I feel pretty good that I was able to do it in one evening.
 

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colin55

Well-Known Member
Those "super-Darlington" transistors are not going to do anything. Their supply is coming from the drive line.

The circuit is far too complex for what it trying to achieve.

Draw a circuit of the voltages you are trying to measure.
 

Mike_2545

Super Moderator
Those "super-Darlington" transistors are not going to do anything. Their supply is coming from the drive line.

The circuit is far too complex for what it trying to achieve.

Draw a circuit of the voltages you are trying to measure.
Those 'super darlingtons' provide the time delay part.

Of course its far too complex, I already said that, but it works.

The circuits of the voltages I am measuring are your average lm337 & lm317 regulators

This 'mess' switches between the two supplies for the digital volt meter to read them
 

colin55

Well-Known Member
If you want to get a "time delay" on the rising voltage, put in a zener. The "rise time" delay you will get with two Darlingtons is less than 3v.
 
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