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Old 19th March 2013, 04:37 PM   #761
AndrewT is online now AndrewT  Scotland
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A Quasi Output Stage uses either all NPNs or all PNPs.
If you want to use complementary transistors, then choose a different amplifier.
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Old 20th March 2013, 06:06 PM   #762
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Quote:
Originally Posted by yehan View Post
any help pls give me a schematic of 550B used the complementary c5200/a1943 for the output stage? Thanks
read first few pages of this thread
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Old 27th March 2013, 06:07 AM   #763
yehan is offline yehan  Philippines
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Help,,,, b550' when i put the power 50 0 50, 15 ampere, the mje 350,340 becomes hot even with out load. And resistor 2pcs, 22k 1/2 watts become hot also. What is the problem thanks...
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Old 27th March 2013, 07:58 AM   #764
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Is that a 50-0-50 AC at the transformer, or 50VDC at the filter caps?

22K?

There are three. The only one that should get hot at idle is the one powering the constant current source. Depending on your rail voltage it may need to be rated at 2W~3W. The feedback resistor, if 1/2W, may get hot during test, it should be OK for music.

The MJE 340/350 run class A, hot all the time. Depending on the rail voltage they may need a small heatsink, they may be dissipating as much as 0.75W, you don't want them over about 85C
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Old 28th March 2013, 06:30 AM   #765
yehan is offline yehan  Philippines
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Thanks djk. How about, when i put the vdc 100 0 100, 15 ampere the circuits not damage? And how much the power? The output trans 10 pair..thanks
I try 5200 2 pair 35vpk sounds good..
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Old 28th March 2013, 06:32 AM   #766
yehan is offline yehan  Philippines
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Quote:
Originally Posted by djk View Post
Is that a 50-0-50 AC at the transformer, or 50VDC at the filter caps?

22K?

There are three. The only one that should get hot at idle is the one powering the constant current source. Depending on your rail voltage it may need to be rated at 2W~3W. The feedback resistor, if 1/2W, may get hot during test, it should be OK for music.

The MJE 340/350 run class A, hot all the time. Depending on the rail voltage they may need a small heatsink, they may be dissipating as much as 0.75W, you don't want them over about 85C


50vdc. Thanks
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Old 28th March 2013, 07:49 AM   #767
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50 VDC will have the 22K for the constant current source running with about 0.45W, I would use a 2W resistor. 65V is 0.77W, I would use a 3W resistor. Most of these size resistors de-rate to zero at 150C, so running at 1/4th rated power inside a 55C chassis will mean the resistor is about hot enough to boil water.

Above the design limit of 65V you will need to change to higher voltage parts for the BC546 and MJE15030/31 and calculate your resistors for the increased power.

I used to buy the blank $6 Pass A40 boards (for the 40W class A design) and change every part on them to run at 95V with six pair of MJ15024/24 for outputs and 2SA1302/2SC3281 for drivers. It would deliver between 600W/4Ω~800W/4Ω depending on the transformer VA.
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Last edited by djk; 28th March 2013 at 07:59 AM.
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Old 28th March 2013, 07:59 AM   #768
yehan is offline yehan  Philippines
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Quote:
Originally Posted by djk View Post
50 VDC will have the 22K for the constant current source running with about 0.45W, I would use a 2W resistor. 65V is 0.77W, I would use a 3W resistor.

Above the design limit of 65V you will need to change to higher voltage parts for the BC546 and MJE15030/31 and calculate your resistors for the increased power.

I used to buy the blank $6 Pass A40 boards (for the 40W class A design) and change every part on them to run at 95V with six pair of MJ15024/24 for outputs and 2SA1302/2SC3281 for drivers. It would deliver between 600W/4Ω~800W/4Ω depending on the transformer VA.
I used mje5032,5033' then mje350'mje350, then the bc546 i change to 2sa970 what resistor i change to handle 100vdcpk. Thanks..
Iwant to get 1000 watts in one channel ten pair 2sc5200 output.
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Old 28th March 2013, 08:08 AM   #769
yehan is offline yehan  Philippines
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Mr djk what is the calculation to change higher voltage. I want 100vdcpk. To get higher wattage output. Instead bc546 i change 2n5551, the 2sa970 the pin not the same...help me to apply 100 volts dc supply.
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Old 30th April 2013, 10:18 AM   #770
yehan is offline yehan  Philippines
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help at negative rail fuse always burn when high volume i used 50volts dc 15 ampere
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