(values are examples only)
transformer secondary has the specs: 9V 4A (no CT)
I need to have 2 power supplies. 1 supply giving out 9V 2A and the other supply is giving out 9V 50mA.
as the title suggested, can I share 1 transformer on the 2 supplies? each supply would have its own bridged diodes.
Thanks for the help.
transformer secondary has the specs: 9V 4A (no CT)
I need to have 2 power supplies. 1 supply giving out 9V 2A and the other supply is giving out 9V 50mA.
as the title suggested, can I share 1 transformer on the 2 supplies? each supply would have its own bridged diodes.
Thanks for the help.
Hi,
simple answer is YES,
But, the two supplies do not float with respect to each other.
The -ve voltage side are at the same effective voltage and the +ve voltage side are at the same effective voltage. They are separated by the diodes only, but there's nothing wrong with that.
The 2A supply will need a more robust diode bridge than the 50mA supply.
simple answer is YES,
But, the two supplies do not float with respect to each other.
The -ve voltage side are at the same effective voltage and the +ve voltage side are at the same effective voltage. They are separated by the diodes only, but there's nothing wrong with that.
The 2A supply will need a more robust diode bridge than the 50mA supply.
jarthel said:
Do the two supplies need to be separated? If no, you don't need two bridges - a single bridge will give you the 9V and that can supply both the 2A and the 50mA circuit.
If they DO need to be separated, this will not work - you need two secondaries, separated from each other.
Jan Didden
Hi,
there is advantage in keeping two bridges and two smoothing sections.
Variable load on one PSU will have less effect on the other PSU. Not quite as good as two separate transformers, but MUCH better than running two supplies from the common bridge and smoothing.
and yes, you can link the two -ve from the bridges to form a common -ve.
there is advantage in keeping two bridges and two smoothing sections.
Variable load on one PSU will have less effect on the other PSU. Not quite as good as two separate transformers, but MUCH better than running two supplies from the common bridge and smoothing.
and yes, you can link the two -ve from the bridges to form a common -ve.
Be careful.
I assumed it would be OK, but the truth is that in one configuration when you connect the bridges together it may short out the transformer secondaries.
I had a set of Peter's amp + PS boards for a 4780. I did not separate them , just connected them back to back and got no sound. Everything worked on its own, each PS board worked fine and the amps worked well when individually tested, but the moment I connected everything together it was silent and no DC.
Eventually I found there is only one way to connect two bridges to a single secondary. The other way, it shorts the transformer out.
I assumed it would be OK, but the truth is that in one configuration when you connect the bridges together it may short out the transformer secondaries.
I had a set of Peter's amp + PS boards for a 4780. I did not separate them , just connected them back to back and got no sound. Everything worked on its own, each PS board worked fine and the amps worked well when individually tested, but the moment I connected everything together it was silent and no DC.
Eventually I found there is only one way to connect two bridges to a single secondary. The other way, it shorts the transformer out.
Even more proof that you should ALWAYS use a series light bulb whenever you restart after maintenance or modification or for first build.
After a single bridge, use two series diodes and filter caps for each consumer if the ground can be common.
Gajanan Phadte
Gajanan Phadte
Hi Gm,
I think the common connection to ground will have the voltage here modulated by current draw from the other operating channel.
I think it is better to have two separate diode bridges, one dedicated to each channel. All it costs is two extra diodes and a little more space.
Now back to why? to save money?
I think the common connection to ground will have the voltage here modulated by current draw from the other operating channel.
I think it is better to have two separate diode bridges, one dedicated to each channel. All it costs is two extra diodes and a little more space.
Now back to why? to save money?
Why...
Your case is one demanding load and other small load, non demanding.
For ur app, the scheme is quite good, but think of devices with multiple boards. The scheme I have shown is better, and is used with additional filtering and regulation.There will be a regulator in the power supply with an extra diode drop. Then these will be supplying to the different application ckts, sometimes on the same board but with demanding multilead ICs with series dide and filtering. This way the bias line noise is reduced.
Gajanan Phadte
Your case is one demanding load and other small load, non demanding.
For ur app, the scheme is quite good, but think of devices with multiple boards. The scheme I have shown is better, and is used with additional filtering and regulation.There will be a regulator in the power supply with an extra diode drop. Then these will be supplying to the different application ckts, sometimes on the same board but with demanding multilead ICs with series dide and filtering. This way the bias line noise is reduced.
Gajanan Phadte
Hi Gm,
common PSU to multiple regulators, that's a good enough why.
Do you really need the isolating diodes when regulating?
common PSU to multiple regulators, that's a good enough why.
Do you really need the isolating diodes when regulating?
No, it is common regulator for multiple loads. This way the filter cap is dedicated to each load because of the the series diode.
Gajanan Phadte
Gajanan Phadte
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