# Peak-and-Hold Circuits

Discussion in 'The Projects Forum' started by irish_, Jun 6, 2012.

1. ### irish_ Thread Starter New Member

Jun 6, 2012
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Hello,

I am new to the Peak-and-Hold Circuit design and I was wondering if anyone could show me some literature/tutorials on the subject. I want to be able to control electromagnets by turning them on and off using this technique. Any help is appreciated, thanks.

2. ### kubeek AAC Fanatic!

Sep 20, 2005
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787
It seems to me you are mixin peak detectors and sample and hold circuits. Since you´re saying controling electromagnets, I would guess sample and hold is the right one, but...
How exactly are the electromagnets controled and what function do you expect from them?

Usually saying what you actually need it to do is much better than asking how to make your way work. You will get there faster without the detour through the solution you chose.

3. ### irish_ Thread Starter New Member

Jun 6, 2012
4
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I am controlling MR Fluid which when no magnetic field is applied, acts like a liquid, but when a magnetic field is induced using electromagnets, it turns to a gel. Cool stuff, the result is almost instantaneous. But I am using it in an apparatus that involves two spinning disks. So we want to control the on and off time of the magnetic field so as to control whether or not the fluid inside the apparatus is a liquid or a solid (gel).

4. ### kubeek AAC Fanatic!

Sep 20, 2005
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How fast do you need the current to change, and what voltage and current do your coils need?

5. ### irish_ Thread Starter New Member

Jun 6, 2012
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We are working in the milliseconds. Like 1-5 milliseconds. The voltage and current are free to be chosen.

6. ### kubeek AAC Fanatic!

Sep 20, 2005
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So you don´t have any electromagnets that already work? Do you know how big magnetic field do you need to control the fluid?

7. ### irish_ Thread Starter New Member

Jun 6, 2012
4
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no, its very early and still in design concept.