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 12/120V inverter again		  New Topic  Reply to Topic
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tim
Mad Scientist

196 Posts
Posted - Dec 15 2006 :  12:41:12 PM  Show Profile  Reply with Quote
hey ken which inverter are you talking about. was it the one i said had a big transformer? where you can get one , well i think this is the only one, and its new i think new old stock.
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tim
Mad Scientist

196 Posts
Posted - Dec 15 2006 :  1:34:26 PM  Show Profile  Reply with Quote
i hope someone out there can help me , i have a TO92 transistor number -KSP44013 that im trying to get the data for and cant find it anywhere.maybe someone knows where to look for it , thanks.
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tim
Mad Scientist

196 Posts
Posted - Dec 15 2006 :  1:38:50 PM  Show Profile  Reply with Quote
in a pwm circuit they use a pnp and npn,the pnp is a 2n5401 so would the voltage be the same as the pnp for the npn . i think this ksp44013 is npn.
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audioguru
Nobel Prize Winner

Canada
3761 Posts
Posted - Dec 15 2006 :  1:56:21 PM  Show Profile  Reply with Quote
It is easy to measure a transistor with a multimeter (diode test) to determine if it is NPN or PNP.
Post the schematic somewhere for us to go and see it.
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tim
Mad Scientist

196 Posts
Posted - Dec 15 2006 :  2:03:49 PM  Show Profile  Reply with Quote
the pnp is the 2n5401 but the other with the number i cant locate i think is npn and there burnt.
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tim
Mad Scientist

196 Posts
Posted - Dec 15 2006 :  2:06:30 PM  Show Profile  Reply with Quote
this inverter im working on just wont start up i substituted the supposed npn and still wont start , and changed all the ics few diodes and few zenars.
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audioguru
Nobel Prize Winner

Canada
3761 Posts
Posted - Dec 15 2006 :  3:48:23 PM  Show Profile  Reply with Quote
Can't you get a service manual or schematic for it?
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tim
Mad Scientist

196 Posts
Posted - Dec 15 2006 :  4:37:10 PM  Show Profile  Reply with Quote
no i wish i could.
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tim
Mad Scientist

196 Posts
Posted - Dec 15 2006 :  5:19:49 PM  Show Profile  Reply with Quote
so is the npn rated lower or higher then the pnp in a pwm circuit.i dont know if its a typical for voltages within these 2 transistors to be the same only that they are pnp and npn.
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tim
Mad Scientist

196 Posts
Posted - Dec 17 2006 :  11:10:30 AM  Show Profile  Reply with Quote
hey people, how critical is it to replace glass zener diodes as far as exact numbers? or can they be matched by use of multi meter ohms or otherwise. these zeners are in a mosfet driver section i guess for voltage spikes.
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audioguru
Nobel Prize Winner

Canada
3761 Posts
Posted - Dec 17 2006 :  12:04:21 PM  Show Profile  Reply with Quote
You can't measure the voltage rating of a zener diode with an ohm-meter. Just look at its datasheet.
Many Mosfets have "a zener diode" built-in from drain to source. It has a very high avalanche current rating.
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tim
Mad Scientist

196 Posts
Posted - Dec 17 2006 :  12:27:32 PM  Show Profile  Reply with Quote
the inverter im working on had a few zeners that were bad and replaced them with what looked the same and i took them from a circuit that also runs on 12 volts.
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tim
Mad Scientist

196 Posts
Posted - Dec 17 2006 :  12:31:12 PM  Show Profile  Reply with Quote
these zeners are in paralle with regular 1n4007 diodes so would the zeners be added protection for the circuit?
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cyclopsitis
Nobel Prize Winner

Canada
729 Posts
Posted - Dec 17 2006 :  2:37:09 PM  Show Profile  Click to see cyclopsitis's MSN Messenger address  Reply with Quote
Ok I've got a question... I've seen on some high current inverter circuits and on some DC PS circuits the transistors' emitter and collectors are put in parallel and the bases are connected to each other. Or in PS transistors are put in parallel again to make the supply able to carry 20 or 30 amps. Does this kind of connection similar to putting batteries in parallel to increase their current capacity?

I have another question too. I was looking at one inverter:
http://www.electronics-lab.com/projects/power/033/index.html
Why does it say "collector is shorted to collector in order to prevent heating"? Why does this stop heating??? I don’t understand this. Those are my questions, thanks!

Ken
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tim
Mad Scientist

196 Posts
Posted - Dec 17 2006 :  3:46:59 PM  Show Profile  Reply with Quote
both the 3055s will be working as one , so less work on the part of 1. i would assume
yea i was looking at that inverter as well.
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