theChris said:
ummm.. I thought the LM4780 was basically 2 LM3886's in the one package.... 4 ohms, because thats what the speakers are..
not sure if theres anything wrong with that schematic.. proabably.. but its how the transformers, bridges, and caps will probably be connected..
Attachments
some of the 47xx lines will put out less power into 4ohms @ 10% distortion.
not a big fan of the circuit due to the 4 full wave bridges and the problems with grounding. basically if one chip pulls signifigant power from a rail, it's ground would be different then the other 4. if they are all connected, then why 4 full wave bridges? a single full wave bridge is all that's needed. possibly 2.
not a big fan of the circuit due to the 4 full wave bridges and the problems with grounding. basically if one chip pulls signifigant power from a rail, it's ground would be different then the other 4. if they are all connected, then why 4 full wave bridges? a single full wave bridge is all that's needed. possibly 2.
pics are fun. you can also use only 1 full wave bridge if you want. using 2 will give more losses (which is something you wanted as it lowers the supply voltage), but also increases frequency. so a capacitor can be smaller. if not the voltage rails will be higher. this setup may be ideal for a subwoofer amp where IMO the extra caps would allow for more depth.
BTW, you can change capacitance as needed.
(edit - changed attachment to correct connections)
BTW, you can change capacitance as needed.
(edit - changed attachment to correct connections)
Attachments
theChris said:
I dunno what the diodes do.... I chose 4 bridges because it makes it easier... 9400uF per rail for the whole amp won't be enough... but if I'm only running 2 channels, then there would be some huge bank of capacitors on each rail, which would be totally unneeded... I need this amp to be versitile.. so I can run anything from it... (within reason) the capacitors are no problem.... I "have" them...
theChris said:
I dunno what they do... I stole the circuit from Rod Elliots site and changed it.... as for the fuses... I proabably should use a single 10amp fuse for all the transformers.. cos as it is, if one fuse blows... I'll probably get huge ofset on the output...
you need a fuse rated higher than the output so ya don't blow it when ya switch it on or under heavy loads... maybe 8amp slow blow...
"I dunno what they do... I stole the circuit from Rod Elliots site and changed it.... as for the fuses... I proabably should use a single 10amp fuse for all the transformers.. cos as it is, if one fuse blows... I'll probably get huge ofset on the output... you need a fuse rated higher than the output so ya don't blow it when ya switch it on or under heavy loads... maybe 8amp slow blow..."
-that's still a lot of amperage. this amp isn't a 600 watt amp is it?
like i said, the PCB is suipposed to be milled very soon. it likely will be milled tomorrow as i have a class with a teacher who does the isolation part. i'd do that myself, but it's like $2k for the software!
i will keep everyone informed on the miniPCBs. i'll try to make some for the other 27pin chips as well. possibly even some of the 15pin chips.
-that's still a lot of amperage. this amp isn't a 600 watt amp is it?
like i said, the PCB is suipposed to be milled very soon. it likely will be milled tomorrow as i have a class with a teacher who does the isolation part. i'd do that myself, but it's like $2k for the software!
i will keep everyone informed on the miniPCBs. i'll try to make some for the other 27pin chips as well. possibly even some of the 15pin chips.
Re: Using a LM4765
Hi Deandob. Can you send your LM4765 schematic to me?
ecstabil@sunpoint.net
deandob said:
Hi Deandob. Can you send your LM4765 schematic to me?
ecstabil@sunpoint.net
Well seems my post got edited - unsafe practices??
NEway you can also wind some more turns on the primary. This can be done without opening up the transformer, just use some hook-up wire which can carry the rated cuurent, and wind about 10 turns around the whole transformer from one of the primary terminals. Keep checking the voltages every 10 turns, until you have about 22 volt on the secondary. I use it all the time to pull down voltages and it seems to work quite well.
NEway you can also wind some more turns on the primary. This can be done without opening up the transformer, just use some hook-up wire which can carry the rated cuurent, and wind about 10 turns around the whole transformer from one of the primary terminals. Keep checking the voltages every 10 turns, until you have about 22 volt on the secondary. I use it all the time to pull down voltages and it seems to work quite well.
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