# Need help making a 12Vdc simple circuit.

#### burkeurban

Joined May 9, 2021
3
I need a 12v dc circuit that will switch between 2 outputs, and reverse polarity each time, automatically. For example, output 1, + -. Then output 2, + -. Then output 1, - +. Then output 2, - +. And repeat.
The order does not matter, the frequency needs to be somewhat slow like at least one or two seconds, it can pulse or be constant, constant would be better.

#### djsfantasi

Joined Apr 11, 2010
7,693
I think this will be a simple circuit.

But it can’t be determined without more data.

What is the outputs driving? Logic levels? LEDs? Lamps? Motors?

And what is the input? A switch? A clock? Logic level input?

Tell us a more about what you’re trying to do...

#### burkeurban

Joined May 9, 2021
3
So, it's wierd. I am trying to make an indoor wind chime, so to say. I have a "coil" from the tube of a CRT tv, above that I am hanging a rod with a neodymium magnet on the free end. The "coil" has 2 sets of 2 contacts on the side. When I use a 12v dc power supply applied to each set and reverse the polarity the "pendulum" swings randomly in a circular arc and would "play" a set of tubular chimes nicely. I want to be able to plug it in and let this happen without standing there with 2 bare wires crossing them and applying them to each set manually.
Here in a bit, if I can figure out how, I'll take a short video and post it so y'all can see.

#### crutschow

Joined Mar 14, 2008
27,229
How much current do the coils take?
Would a slightly random pattern of pulses be better, or is equally spaced pulses okay?

#### burkeurban

Joined May 9, 2021
3
How much current do the coils take?
Would a slightly random pattern of pulses be better, or is equally spaced pulses okay?
Regarding the pulse timing, I don't believe it would matter, whichever is more simple.
I have used both 4 and 5 amp power supplies, I am sure it can take more or even less and still operate. I'll shoot a video tomorrow and show y'all what I've got and demonstrate, manually, the affect I am trying to achieve

#### crutschow

Joined Mar 14, 2008
27,229
I have used both 4 and 5 amp power supplies, I am sure it can take more or even less and still operate.
Are you saying that the power supplies are current limiting at 4 or 5 amps when the coil is powered?

#### Irving

Joined Jan 30, 2016
1,540
I doubt the TS can answer that or has the equipment to measure it.

Let's try a different tack.

What size TV did this yoke come from? If you know the make and model number that would be even better.

Do you get the same response from both coils or is one 'stronger' than the other?

How are you connecting and reversing the power supplies atthe moment? By hand, just touching the wires to the coils or what? Edit: yes, I now see you said that, doh!

Do you get a big spark on disconnection?

If you can't manage a video, take a few good hi-res & in-focus pictures of it from 2 or 3 angles.

#### DickCappels

Joined Aug 21, 2008
7,442
Or even easier, if the power supply has a current meter, take note of the current drawn as the coils are energized. Do you have a multimeter? With that you could measure the coil resistance.

#### LowQCab

Joined Nov 6, 2012
558
Here's how ya do it ........
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#### neonstrobe

Joined May 15, 2009
153
Looks to me like you've got the op-amps in common mode?
Shouldnt they be driven from Q, -Q?

#### Irving

Joined Jan 30, 2016
1,540
I think that circuit is correct as drawn. The two flip-flops as arranged will produce quadrature outputs at Q1, Q2:

Q1 Q2
0.....0
1.....0
1.....1
0.....1
0.....0 etc

The op-amps are arranged as two 'inverting and non-inverting' pairs, so the effective drive to the yoke will describe a 'circle', assuming both coils are identical (which isn't generally the case for a TV yoke.)

#### LowQCab

Joined Nov 6, 2012
558
Notice the different part numbers.
Those are MOSFET Gate-Drivers, and 2 of them have an inverting Input.
I probably should have gone to the trouble of putting the little Inverting-Circle-Symbols on
the Inputs of the 2 Inverting units.
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