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Author Topic: PROBLEM SOLVED: How do I get alternating current from a battery pack?  (Read 1553 times)
elShoggotho
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« on: February 24, 2011, 10:15:05 am »

So here's the problem: I've disassembled a pair of active speakers. For the sole reason of making my life miserable, they run on alternating current, with no real way to find out where the rectifier is on that tiny circuit board. Obvious solution: give them AC. That's where the problem starts. Batteries are DC sources, and my electronics knowledge is only sufficient to find out what needs to be done, but not how. I need an inverter or similar circuit. Since inverters are usually huge, I need to go smaller. That means using a NE555 timer to generate a square wave at roughly 50 hertz.

So: How do I wire the NE555 to generate that square wave?
« Last Edit: February 26, 2011, 02:18:08 pm by elShoggotho » Logged
Antipodean
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« Reply #1 on: February 24, 2011, 10:29:49 am »

555 timer - http://www.doctronics.co.uk/555.htm. You will find the timing componets for the frequency you are after and pin3 (output) is a square wave.

There is every posibility that the circuit in your active speakers recifies the voltage to DC, in which case you could use DC anyway. Otherwise there would always be a hum on the speakers.
The only issue is if the speakers uses a plus and minus rails then you might have a problem.
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« Reply #2 on: February 24, 2011, 04:41:53 pm »

You need an AC/DC adaptor.
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elShoggotho
Guest
« Reply #3 on: February 26, 2011, 12:17:24 pm »

You need an AC/DC adaptor.
Well, duh.
I actually checked the circuit, and seem to have found the right place to put a battery.

UPDATE: Yep, found the spot. The switch assembly comes directly behind the rectifier, with convenient metal loops to solder stuff to. Replaced the switch in the process, since the old switch assembly would short out the battery. Now I can switch between off, battery and mains power. Mains still comes in as AC and runs through an onboard rectifier, the battery pack connector is soldered directly to the switch. Sometimes, the easiest solution is the best.
« Last Edit: February 26, 2011, 02:26:10 pm by elShoggotho » Logged
Dr. Madd
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« Reply #4 on: February 26, 2011, 07:18:12 pm »

Sorry. Sometimes throwing an obvious answer out, gets it out of the way, you know.
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Drew P
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« Reply #5 on: February 27, 2011, 02:18:25 am »

yes,but then,it should be a dc/ac inverter Wink
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