#1
For my top secret UBER cool project, which shall be shared with the UG community if it ever works, I need a way to very quickly raise and lower the voltage (coming from a 9v source) Is this possible? Any ideas?

Cheers.
#2
unplug and plug it in? or have an on/off switch for a voltage resistor/attenuator?
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Shwiggity.
#3
Needs to be done automatically, by the way (i'm talking about once every half a second)
#5
a bunch of resistors and a momentary switch? idk
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#6
Oscillator circuit sounds like it'd work... hook one of them to some resistors and have a go at that?
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Shwiggity.
#8
You want to create a DC pulse of 9V on and off every 500mS or you want an AC waveform of 9V pk-pk oscillating at 2Hz (once per 500mS)?

If you want an on/off pulse, look into the 555 timer IC

If you want an AC sine wave, look into a Wien Bridge or RC oscillator

You can also produce triangle waves, or any other complex waves you like.

If you post a bit more info about what your trying to do, I can provide you with a schematic if needed
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#9
Quote by wilson479
You want to create a DC pulse of 9V on and off every 500mS or you want an AC waveform of 9V pk-pk oscillating at 2Hz (once per 500mS)?

If you want an on/off pulse, look into the 555 timer IC

If you want an AC sine wave, look into a Wien Bridge or RC oscillator

You can also produce triangle waves, or any other complex waves you like.

If you post a bit more info about what your trying to do, I can provide you with a schematic if needed



What i'm trying to do, is make an e-bow type device, where an electromagnet attracts the string, then dies, so the string returns to it's normal position, then come on, so the string raises up again, and so on.

It's the DC alternator i'm interested in.
Thanks
#10
So it will be the timer circuit you need to build, and use the output from that to drive your electromagnet.

Check out this link: http://www.uoguelph.ca/~antoon/gadgets/555/555.html

With a time constant built from a 470k ohm resistor and 1uF capacitor (read the link to understand) and a power supply of 9V DC, you should be able to drive a 5V solenoid / relay once every 470mS quite easilly. Thats just over two pulses per second.
-Keep on listening to the great Joe Strummer. Cos through music, we can live forever.
#11
I'm not sure if this will affect your project or not, but if you raise and lower voltages very quickly, e.g switch 9v to 18v through EMGs you will get a loud popping noise.


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#12
Forget all this fancy electronics.
Set up a gear driven reciprocating assembly with a small onboard 9v electric motor to make it turn a dimmer switch for a light fixture.
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