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Old 4th July 2007, 08:31 AM   #2141
microp is offline microp  Latvia
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Default Heatsink for driver...

!? It should be good enough for both...
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Old 4th July 2007, 09:07 AM   #2142
Nordic is offline Nordic  South Africa
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Carlos illustrated before that they only need 1 square inch of plate for heatsinks each... I have tiny TO220 sinks on mine and I can't feel them heat up at all.

Just make sure the transistors are isolated from each other if they are going to share a sink... that one from a PC power supply?
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Old 4th July 2007, 09:23 AM   #2143
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Default You Casio Ex Z60 is producing good images


Your supply is perfect..... 500 watts is fine to hold two channels full power over 4 ohms.

The bass will be alike a punch into your breast ..... hehe.... earthquake in Látvia.

regards,

Carlos
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Power supply; ripple, filter, noise, stability and the use of capacitance multiplier... Portuguese and English; https://www.youtube.com/watch?v=sSm0ku1eIgg
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Old 4th July 2007, 09:24 AM   #2144
microp is offline microp  Latvia
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Default Yes this is from PC power supply...

They are isolated... i didn't find nothing smaller and I don't have metal scissors to cut it smaller.
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Old 4th July 2007, 09:27 AM   #2145
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Default No problems...keep the big ones!


Will work cool this way...... less bias drift..... will help you to work stable.

Keep them in place.

regards,

Carlos

.................................................. .................................................. .....

Nordic

He is using the big one because have not tools to cut the metal.

Bigger is better than smaller..... your size is perfect Nordic.....but having bigger will not produce problems.

You output transistor, for example, are working warm...they will last for ever..... your grandson will be listening Dx amplifier.... as working cold, only electrolitic condensers will need replacement in 50 years more.

regards,

Carlos
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Old 4th July 2007, 09:33 AM   #2146
microp is offline microp  Latvia
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Default Re: Yes dear Microp...you will bother people living near you.

Quote:
Originally posted by destroyer X








For safety reasons...please, do this test:

Produce a short circuit into the input... alive shorted to ground... so..no signal at the input....now install your speaker or keep it installed if already made.... hold your multimeter and turn it to read AC volts.... 20 volts is fine position...now measure the output... any AC voltage can be present there... having voltage you will be having oscilations that are heating your unit...check it.


Carlos


On output multimeter shows nothing... zero
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Old 4th July 2007, 09:38 AM   #2147
microp is offline microp  Latvia
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Default I will connect 10ohms resistors and...

will test bias and DC offset again...
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Old 4th July 2007, 09:44 AM   #2148
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Default A very good idea to check bias and offset once more.


Zero is correct.... no oscilations.... perfect.

And after you finish...let the amplifier running into some resistive load.....do not need to be full power as you will have problems with the resistance heat....but force it to warm a little.

You can use a hair drier to heat it up too.

Then check you bias once more..... do not re-adjust.... as when turn cold it will return to the stand by point once more.

Will be a good experience to see the thermal drift.

Are you using VBE multiplier?

regards,

Carlos
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Power supply; ripple, filter, noise, stability and the use of capacitance multiplier... Portuguese and English; https://www.youtube.com/watch?v=sSm0ku1eIgg
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Old 4th July 2007, 09:51 AM   #2149
microp is offline microp  Latvia
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Default Yep... I am using Vbe multiplier

checking bias now....


it is little bit warm even when input is shorted to ground....
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Old 4th July 2007, 09:54 AM   #2150
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Default Reduce your bias to 600 milivolts over 10 ohms resistance


This way you will have it cool.

The temperature will be hard to feel touching.

Those drivers current are limited by the 180 ohms resistance that is installed "floating" between drivers emitters.

You can increase a little if you need.... till 270 ohms will work fine.

Increasing you will perceive more treble.... decreasing the effect will go to bass.

You will have around 4 to 4.5 watts of heat during stand by mode...without signal.... this heat will be perceived when the heatsink is too much small.

Tweaking this resistance you will need to readjust your amplifier.

regards,

Carlos
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