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Class D Switching Power Amplifiers and Power D/A conversion

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Old 4th March 2007, 06:32 PM   #371
Baldin is offline Baldin  Denmark
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From above:
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Old 4th March 2007, 06:34 PM   #372
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Old 4th March 2007, 06:40 PM   #373
Baldin is offline Baldin  Denmark
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From the back .....

Why are Specon connectors only used for prof use???

They are such good conectors, takes up to 4 mm^2, can be pluges in while the amp is turned on. They are quite inexpensive compared to all things golden. Can only be recommended
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Old 4th March 2007, 06:45 PM   #374
BWRX is offline BWRX  United States
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But there was a problem with a high pitched tone being present all the time.

Think I've heard this before, when trying to put two amps in one case. As I recall it should help moungint the two amps as close together as possible .... but that was what I thought I hade already done.

Would it help syncronising the amps??
And hould bould that be done as easy as possible??

IT also have some 100 Hz "noise" .... gues it comes directly from the PSU.

Hi Baldin. Does the high pitched noise go away if you only have one module powered? If so, the two modules are definitely interacting. It may help to physically space them farther apart.

Reloacte the rectifier side of the power supply board as far away from the module wiring as possible. That should help reduce the 100Hz noise a bit. Also try twisting the power supply wiring together for each module if possible.
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Old 5th March 2007, 04:13 PM   #375
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I found a RM core, but the material is N27.

From a quick search on the net, this material is made by Siemens, and intended for power transformer below 100khz.

Is this RM core (N27) can be used for UCD output filter (with fosc near 500khz)?
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Old 27th March 2007, 12:21 PM   #376
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Has anybody experience this? When the mosfet's heatsink is attached to the case (=grounded), the residual output get distorted (sinusoidal becomes wrecked)?

How to counter this? The heatsink needs to be grounded, how to advoid this? I think this is because the low side Drain actually=full swing, and when this transistor gets grounded, it forms a capacitor between transistor's base metal plate (=full swing) and heatsink (=ground).

Is this why the real UCD uses plastic mosfets?
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Old 27th March 2007, 12:33 PM   #377
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You should isolate the Fets from the heatsink by using appropriate TO220 insulating heat transfer material. Otherwise you would have a short from the supply rails to ground every time a fet switches ON.
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Old 27th March 2007, 12:46 PM   #378
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My apology: Mounting the top fet directly to the heatsink (ground in your case) will short the positive rail to ground. Also, when the bottom fet switches on, you will be shorting the negative rail to ground. Use thermal insulating material.
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Old 27th March 2007, 12:52 PM   #379
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Hi, Stephano,

I've used insulation mica and goop. The effect is very obvious. Do you also see this in your UCD?
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Old 28th March 2007, 04:27 AM   #380
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The insulation material used in UCD400 and UCD700 looks thick, white coloured. Maybe it will reduce the capacitance effect between transistor flange and heatsink/ground.

What insulation material is it?
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