thermionic
Well-known member
- Joined
- Jun 3, 2004
- Messages
- 1,671
Hi,
I'm involved in developing a limited-run product. Obviously, an external CE / UL-approved wallwart is an attractive option for power. Bearing in mind that the relays alone will take anything up to 250mA, and wallwarts with AC outputs becoming an endangered species, it appears that the only option will be to opt for an SMPS wallwart. I will need a maximum of 100mA per rail for the audio.
My current thinking is as follows:
1.25A SMPS Wallwart - directly to relays
1.25A SMPS Wallwart also feeds 2x+/-24V Dual DC-DC Converter - to - LM317 / LM337 (traditional design, set to output +/-18v).
The analogue circuitry will be divided into 2 halves, with each being fed by a different LM317 / 337 pair
The drop from +/- 24v to +/-18v is likely to create a fair amount of heat...
The easiest way to do this would be with an external AC adaptor, skipping the DC-DC convertors, but I just can't find one powerful enough... The option outlined above isn't cheap, or efficient. Can anyone think of a better way?
Thanks in advance.
Justin
I'm involved in developing a limited-run product. Obviously, an external CE / UL-approved wallwart is an attractive option for power. Bearing in mind that the relays alone will take anything up to 250mA, and wallwarts with AC outputs becoming an endangered species, it appears that the only option will be to opt for an SMPS wallwart. I will need a maximum of 100mA per rail for the audio.
My current thinking is as follows:
1.25A SMPS Wallwart - directly to relays
1.25A SMPS Wallwart also feeds 2x+/-24V Dual DC-DC Converter - to - LM317 / LM337 (traditional design, set to output +/-18v).
The analogue circuitry will be divided into 2 halves, with each being fed by a different LM317 / 337 pair
The drop from +/- 24v to +/-18v is likely to create a fair amount of heat...
The easiest way to do this would be with an external AC adaptor, skipping the DC-DC convertors, but I just can't find one powerful enough... The option outlined above isn't cheap, or efficient. Can anyone think of a better way?
Thanks in advance.
Justin