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circuit for pulsed output at 10Hz

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p_eter_d

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using a 9v dc power supply I would like to build a circuit that produces a pulsed dc output at 10 Hz. I would like to power a small coil to produce a pulsed magnetic field at 10Hz.

Any help would be greatly appreciated.
 
Use a 555 timer configured as an astable multivibrator (Google will turn up many designs).

Depending upon the coil current you may have to add a transistor driver at the 555 output. Do you know its resistance?
 
Need some more information - how big is the coil? Are you looking for a sine wave, or low duty cycle square wave? Do you know the coil's current draw or DC resistance? A simple 555 might be the thing, but it may need an external drive transistor depending on how much current there is.
 
Thank you very much for the replies, I will be wanting a square wave output and im not sure of the coil size yet, i'm still just leaning the basics and will experiment with different coil sizes.

Thanks for pointing me in the right direction, very much appreciated.
 
Measure the resistance on your coil, it shouldn't be less than about 50Ω for a 555 and a 9V battery.
 
View attachment 61979

I have my timer circuit output at 10hz, 7.4V and a 50% duty cycle. The measured current of the output is 300mA.

will measuring a pulsed current with a multimeter give me an accurate measurement?


The coil I have has a resistance of 5Ω, so I plan on adding a resistor (50Ω or greater) to get the desired current.

should I also have a diode on the output? is back emf a concern?
 
The 555 can sink more than it can source, so you may want to connect one side of the coil high instead of to ground. Back EMF could kill the 555, so a diode is in order. Any general-purpose rectifier like a 1N4004 would be good enough for this. Here's how to connect it:

coilckt.gif

Always keep the back-EMF diode pointing to the positive side of the coil.

If you can increase the windings to raise the coils resistance, that will give you a more efficient circuit than adding a resistor. At this low frequency, if you have a 5Ω coil and a 45Ω resistor, 90% of the power will go to heating the resistor and only 10% will go to the coil's field.

Mind if I ask what are you building?
 
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the claims are impressive
Wild claims are made for all sorts of 'therapeutic' gadgets and spoof videos are too easy to make these days. Personally I can see no reason why this device would work, but I would love to be proved wrong. I wish you luck with the project and good health. Keep us posted.
 
The video says the device costs $2000.00 and is rented for $35.00 per week.
Only 2 people tried it and liked it. It took a few weeks of treatment before the pain went away. Maybe the pain would go away in a few weeks with no "treatment"?

Why do you think a weak and cheap little 555 is as powerful as the device?
How and at what frequency will you pulse it?

Medicine:
1) Take a very expensive treatment for one week and your cold will go away.
or
2) Do nothing for one week and your cold will go away.
 
I'm glad you are building it yourself instead of sending them money. Hope you get well soon.
 
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