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Old 10th October 2012, 09:09 PM   #21
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The sinewaves are a lot different than they were before! hanging around in the middle between on and off O.o
but it moves the subwoofer forwards (outwards) and backwards (inwards) this time around!
and I'm not using a darlington transistor... I checked it's a normal transistor I got from a broken TV motherboard
and I checked it on the data sheet its only a single transistor not a darlington!.. yikes!!
I'm looking for a specific transformer to reduce the DC going to the output
is there one that can work for a 4ohms subwoofer?
it is 4ohms 175 watts rms 500 watts max
and it is a DUAL brand it's cheap but hits hard enough for me
or is there another way to reduce the DC using something other than a transformer?

Last edited by realflow100; 10th October 2012 at 09:31 PM.
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Old 11th October 2012, 06:41 AM   #22
Mooly is offline Mooly  United Kingdom
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Yes, this version phase inverts the signal. Use of a single transistor rather than a darlington means the input impedance is very low and the coupling cap at the input needs to be big.

You have a lot to learn on amplifier design A transformer used as the collector load would work but it would have to be purpose built. You won't find one for this.

No, the way forward is to look at simple multistage amplifiers that use capacitor coupling. That could be done with a one transistor amp but it would be inefficient.
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Old 11th October 2012, 10:31 PM   #23
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wow that's terribly inefficient compared to mine O_o
I tried using a turdly transformer used in a AC to AC power supply but it didn't have the output/input voltage and ohms and whatnot that I need to get proper power out of my subwoofer... O_o
isn't there some audio transformers that are made for this job? couldn't someone direct me to a website that shows what I would need? I mean surely there's someone on the planet that has an audio transformer that's made for this job!

unless its better to just try the capacitor thingy how would I go about doing that?
i'm curious but idk how to do it.

Last edited by realflow100; 11th October 2012 at 10:35 PM.
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Old 11th October 2012, 11:05 PM   #24
sreten is online now sreten  United Kingdom
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Hi,

Meanwhile in the real world things carry on as normal.

rgds, sreten.

4700uF electrolytic should be put in series with the driver,
-ve terminal to the driver +ve terminal to the amplifier.
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Last edited by sreten; 11th October 2012 at 11:08 PM.
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Old 11th October 2012, 11:18 PM   #25
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I don't have one of those that big.... do you mean 470uf? or 4700uf? and I've already tried a bunch of different combinations of capacitors in series with my speaker and every time I try I get absolutely no sound out of my speaker whenever I wire a capacitor in series with the speaker
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Old 11th October 2012, 11:25 PM   #26
sreten is online now sreten  United Kingdom
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Hi, wrong capacitors, rgds, sreten.
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Old 12th October 2012, 08:22 AM   #27
Mooly is offline Mooly  United Kingdom
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Quote:
Originally Posted by realflow100 View Post
I don't have one of those that big.... do you mean 470uf? or 4700uf? and I've already tried a bunch of different combinations of capacitors in series with my speaker and every time I try I get absolutely no sound out of my speaker whenever I wire a capacitor in series with the speaker
You won't get sound wiring it just in series. Look at my diagram above. You need a collector load resistor (R1) and to take the audio from that via the cap. 4700uf would be typical for a large speaker but anything above 470uf will work OK to test it.
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Old 12th October 2012, 12:54 PM   #28
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Smile fun

Quote:
Originally Posted by Mooly View Post
The mk2 version. And it works... sort of. (we think the transistors a darlington if I remember correctly)

realflow100, there is one fundamental difference between this amp and your first. Can you see what it is ?
hi
mine is better, efective full class B with zero idle
but ac sims show hf oscillations
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Old 12th October 2012, 02:19 PM   #29
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I can't see Realflow's version.
Where is the link to his schematic?
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Old 12th October 2012, 06:12 PM   #30
Mooly is offline Mooly  United Kingdom
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Quote:
Originally Posted by AndrewT View Post
I can't see Realflow's version.
Where is the link to his schematic?
This was the original as far as we know,
I finally made a good working transistor amplifier

we deduced the circuit from the point to point wiring description.

Do you not see the circuits in post 17 and 22 in this thread Andrew ? They are as close as we can get from the descriptions.
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