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Old 20th April 2010, 04:03 PM   #101
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Quote:
Originally Posted by apexaudio View Post
Do not powering up without heatsink, drivers transistor work in class A.
Don't forget wire jumper on coper side pcb.
Don't forget to connect input GND.
Use 150R 20W on primar ac transformer.
U can use 100R instead fuses, I don't, but I made 1600 amplifiers still now.
Check DC offset before connect speakers, use 100uF bipolar if U want test amplifier without protect.
Good luck!
Regards
this is my heat sink
can i use step down transformer in testing since i don't have a variac
220v is our mains here i'm planning to step down to 110v,is this a good idea?
how about light bulb which is better to put in primary or in secondary?
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Old 20th April 2010, 04:19 PM   #102
wg_ski is offline wg_ski  United States
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If you use a light bulb limiter, you don't need to step it down first or use any DC protect. The light bulb is actually better than a variac. A lot of amplifiers will work perfectly at lower voltage and get unstable at full voltage. With a variac turned down it may behave, and then go bang very suddenly as it is brought up. The light bulb will let the amp get to 90% of normal voltage when it's idling, and bring it down automatically if it goes unstable.
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Old 20th April 2010, 04:33 PM   #103
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Quote:
Originally Posted by engel dela pena View Post
this is my heat sink
can i use step down transformer in testing since i don't have a variac
220v is our mains here i'm planning to step down to 110v,is this a good idea?
how about light bulb which is better to put in primary or in secondary?
Just put 150R 10-20W in primary.
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Old 20th April 2010, 04:52 PM   #104
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Quote:
Originally Posted by wg_ski View Post
If you use a light bulb limiter, you don't need to step it down first or use any DC protect. The light bulb is actually better than a variac. A lot of amplifiers will work perfectly at lower voltage and get unstable at full voltage. With a variac turned down it may behave, and then go bang very suddenly as it is brought up. The light bulb will let the amp get to 90% of normal voltage when it's idling, and bring it down automatically if it goes unstable.
I agree, but I don't use bulb, and can't suggest without my expirience. What will be bulb specify?

Last edited by apexaudio; 20th April 2010 at 05:12 PM.
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Old 20th April 2010, 05:41 PM   #105
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hi engel dela pena
greetings use 100 watt bulb in series with primary winding

thanking you
andrew lebon
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Old 20th April 2010, 07:56 PM   #106
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Bulb have positive temperature coefficient (PTC). When bulb is cold it have small resistance, when current rising bulb get hot and resistance is R=U2/P. U=220v, P=100w and R=484R when bulb bright, that resistance will drop voltage on primary and protect amplifier if something is wrong.
Resistance of 150R will drop voltage on primary if current rising. Voltage on primary will be U=220v-150RxI(A), voltage drop will protect amplifier is something was wrong also like bulb.
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Old 21st April 2010, 02:30 AM   #107
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Quote:
Originally Posted by engel dela pena View Post
what particular ink are you using
that is not a ordinary silk screen embosed ink
I just print layout PCB, my friends is specially work in advertising which transfer in PCB. I don't know what ink in used..
Regards,
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Old 21st April 2010, 11:27 AM   #108
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goooooooooood
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I respect both know sincerely
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Old 21st April 2010, 01:14 PM   #109
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I don't see clear, but led must look directly to ldr, and light cause drop resistance of ldr.
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Old 21st April 2010, 01:26 PM   #110
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Originally Posted by elgafary View Post
goooooooooood
Give us some more words, what do you mean?

Last edited by apexaudio; 21st April 2010 at 01:33 PM.
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