eurorack power supply

Thread Starter

tsope

Joined Jan 10, 2021
5
hi guys and girls
need your help, i am trying to reverse engineer a power supply for eurorack as it is way too extensive and the part are way cheaper.
i have already did most of the job as far as i can and overlaid on the attached picture.
i need your help figuring out the resistors values and recommend a good voltage regulators as the ones used in this power supply are hidden.
also, i am planning on using 2 mean well irm-30-15 instead of 2 different power supplies as used in the original as it will be easier to build on a prototype board this way, do you recommend it or should i use the same power supplies as in the original.
finally, there are 2 hidden components hidden under the heat sink that i have marked as "resistor?!?" next to the voltage regulators in my picture as that is what i think they are, what do you think ? and if you also think they are resistors, what values should i use?
thanks to all and happy new year
 

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Veracohr

Joined Jan 3, 2011
757
Since the outputs are +/-12V and the power modules are 15V, the heat sinked parts are probably linear regulators and the resistors are for those. Look up the LM7812 & LM7912 to see example circuits with resistor values.
 

Thread Starter

tsope

Joined Jan 10, 2021
5
thanks veracohr
they are linear regulators indeed. the ones you have recommended are only 1a and i need 2a, also what do you think on using 2 of the same power supplies instead of 2 different ones as in the original?
 

Veracohr

Joined Jan 3, 2011
757
You can use a pass transistor to boost the current capability of the linear regulator. The LM317 datasheet bertus posted gives an example of it. I think that method should work for a fixed regulator like the LM7812 as well.
 

bertus

Joined Apr 5, 2008
21,451
Hello,

Keep in mind that the 15 volt power supplies are 2 A for the positive and 1.4 A for the negative side.
You can never pull 2 A from the negative side.

Bertus
 

Thread Starter

tsope

Joined Jan 10, 2021
5
Hello,

Keep in mind that the 15 volt power supplies are 2 A for the positive and 1.4 A for the negative side.
You can never pull 2 A from the negative side.

Bertus
that is fine, in eurprack the positive line is the one under heavy load. in the system i am planning it will drew 4a from the positive and only 1.6 from the negative, so 2 of those power supplies should do. as for your reply, i am planning on using the same kind of power supplies both for the positive and the negative. worst case, I'll just use 4 power supplies but it would be easier to just use 2
 

Thread Starter

tsope

Joined Jan 10, 2021
5
You can use a pass transistor to boost the current capability of the linear regulator. The LM317 datasheet bertus posted gives an example of it. I think that method should work for a fixed regulator like the LM7812 as well.
i am trying to keep the circuit as close to the original as possible and i think that using pass transistors may add noise to the output. as it is intended for a synthesizer the power needs to be as clean as possible. I just need to find a recommended linear regulator for eurorack as i have read that some can be noisy. i guess it's research time. thanks for the quick reply
 
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