I dont have a need to, but in the event of more needed power, is it possible to parallel 7812 chips to achieve more than 1A of current?
Loading resistors would be used to regulate the load sharing.
-Paul
Loading resistors would be used to regulate the load sharing.
-Paul
Never!
7812 or other voltage regulators are low output impedance voltage source. Even very tiny output voltage difference between two 7812 chips would lead to a large amount of current flowing between them.
Take a look at the 78XX application note and there are simple methods to increase its current capability. One suggestion would be using bypass transistor.
7812 or other voltage regulators are low output impedance voltage source. Even very tiny output voltage difference between two 7812 chips would lead to a large amount of current flowing between them.
Take a look at the 78XX application note and there are simple methods to increase its current capability. One suggestion would be using bypass transistor.
Uhm, you're off by 20 times. The S series are Small, for 100mA or so...in TO-92 cases.
Unless I missed something in the past 5 years...(likely since I'm a toob guy 🙂 )
Tim
Unless I missed something in the past 5 years...(likely since I'm a toob guy 🙂 )
Tim
This Is Funny...
Hi Tim,
D'Haen is a toob guy, so are you and so am I...
One thing I know though the S version is good for 2A.
The T version is even good for 3A.
Cheers,😉
Hi Tim,
D'Haen is a toob guy, so are you and so am I...
One thing I know though the S version is good for 2A.
The T version is even good for 3A.
Cheers,😉
Paul to your origignal question....you can parallel with some power resistors to equalise the load...but the cheaper or better way is to use a pass transistor
Cheers!!The DIRT®
Cheers!!The DIRT®
I have looked at trying to use a bypassed regulator for my upcoming amp project, but I was wondering if there were any pass designs which allow the retention of the curent limiting present in the regulator, to give some protection against a short at the speaker terminals.
find the 3 terminal regulator application notes-national
can't beat it for telling you how to do all with a 78xx/317
can't beat it for telling you how to do all with a 78xx/317
Bigparsnip(LOL)....you can use a technique called fold back current limiting....it will drop the regulator down to zero volts if a short is detected or the circuit is drawing more amperage than the regulator can supply
I realise that the regulator will do this, but I was wondering if anyone had any circuits out there already that I could use to bypass the voltage regulator (to allow MUCH bigger currents to flow)whilst still maintaining this ability for the regulator to limit the current. As, with most of thee things I have come up with so far either dissapet a lot of heat or have no limit on the current which can flow in the bypass transistors.
However, having a look around, I'm not too sure I should do this, as I'm not to sure the voltage regultor would be fast enough to keep up with the varying demands of a class AB power amplifier. So I was thinking I might try and build my own design using a fast op-amp as an error amplifier driving an output stage in relation to a regulated reference (using a zenner and constant current scource). The only problem with this is I will pretty much need to build two power amp style output stages which could get expensive and would need even bigger heatsinks.
I guess I should ask arround to see if there is anyone out there who has built anything with a large power output (+/- 55V at up to 25A possibly bridged if I ever find big enough speekers) which has a regulated supply, as to date I have only heard roumers about one Krell product which uses a regulated supply for it's power stages (I should go an have a look for it I guess).
anyway, enough for now, but please let me know if you think it would be possible/worthwile improvement to a power amp project.
However, having a look around, I'm not too sure I should do this, as I'm not to sure the voltage regultor would be fast enough to keep up with the varying demands of a class AB power amplifier. So I was thinking I might try and build my own design using a fast op-amp as an error amplifier driving an output stage in relation to a regulated reference (using a zenner and constant current scource). The only problem with this is I will pretty much need to build two power amp style output stages which could get expensive and would need even bigger heatsinks.
I guess I should ask arround to see if there is anyone out there who has built anything with a large power output (+/- 55V at up to 25A possibly bridged if I ever find big enough speekers) which has a regulated supply, as to date I have only heard roumers about one Krell product which uses a regulated supply for it's power stages (I should go an have a look for it I guess).
anyway, enough for now, but please let me know if you think it would be possible/worthwile improvement to a power amp project.
Re: Never!
Sorry, but this isn't true because they aren't bidirectional. What happens is that one of the regulators (the one with slightly higher voltage) delivers all the current up to it limits the current, after that the second one will add current.banana said:
parallel regulators
Actually you will probably wind with an oscillating circuit since a voltage regulator is an amplifier with a large DC offset voltage and no input signal. If you had very closely matched voltages you could probably add a 0.1 ohm resistor to the output of each regulator and run the circuit from the junction. You would need to have an output cap at the output of each regulator before the summing resistors. You can also add a bypass cap to ground the junction of the two resistors. I have seen this done to increase to current capacity of the regulator circuit. Trimming the DC current for each is not that hard. AC stability is a bigger issue.
Actually you will probably wind with an oscillating circuit since a voltage regulator is an amplifier with a large DC offset voltage and no input signal. If you had very closely matched voltages you could probably add a 0.1 ohm resistor to the output of each regulator and run the circuit from the junction. You would need to have an output cap at the output of each regulator before the summing resistors. You can also add a bypass cap to ground the junction of the two resistors. I have seen this done to increase to current capacity of the regulator circuit. Trimming the DC current for each is not that hard. AC stability is a bigger issue.
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