In my chipamp I've got dual25V secondaries feeding carlosFM snubber board givng approx +-36V
Now I want to add an electronic crossover requiring +-15V.
I had hoped to just use 15V reglators to drop the 36V, but the National ones only take input up to 30V.
What are my options (without adding a suitable trafo)?
Are there 15V regulators that will take my 36V?
Should I cascade regulators, say 24V reg followed by 15V.
Or do I just need some other circuitry around the 15V regs.
Something I can build on strip board is required.
Thanks
Jim
Now I want to add an electronic crossover requiring +-15V.
I had hoped to just use 15V reglators to drop the 36V, but the National ones only take input up to 30V.
What are my options (without adding a suitable trafo)?
Are there 15V regulators that will take my 36V?
Should I cascade regulators, say 24V reg followed by 15V.
Or do I just need some other circuitry around the 15V regs.
Something I can build on strip board is required.
Thanks
Jim
Hi Jimbo
You can, as DoctorJ said, use diodes. 4007 will drop about 0,7V. You can also use the LM317 and LM337. Those take up to 37V in- and output. I would surely put any regulator on a small heatsink!
Erik
You can, as DoctorJ said, use diodes. 4007 will drop about 0,7V. You can also use the LM317 and LM337. Those take up to 37V in- and output. I would surely put any regulator on a small heatsink!
Erik
I generally used a pre-regulator either a transistor type or a LM78XX / 79XX i.e, using the 24v ones and take advantage of further ripple reduction. Plus the heat is spread over a larger area.
Or you could use a series zener (work out the power rating) or a string of diodes as suggested.
Cheers
Or you could use a series zener (work out the power rating) or a string of diodes as suggested.
Cheers
I've just had another look at some specs, eg LM7915 will take 30V input-output differential.
But LM340/7815 says +35V absolute max.
Sounds like that limit shouldn't be pushed?
But LM340/7815 says +35V absolute max.
Sounds like that limit shouldn't be pushed?
Jimbo,
The proper approach to this depends on the load current. For example, if it's a few mA, you might be able to use a three terminal regulator with a zener in the input lead.
If you need an amp, and the high voltage supply can support this, then you need a regulator with a series pass transisor and maybe a dropping resistor in the collector to drop the excess voltage. You also need heatsinks to keep these parts from overheating.
Rick
The proper approach to this depends on the load current. For example, if it's a few mA, you might be able to use a three terminal regulator with a zener in the input lead.
If you need an amp, and the high voltage supply can support this, then you need a regulator with a series pass transisor and maybe a dropping resistor in the collector to drop the excess voltage. You also need heatsinks to keep these parts from overheating.
Rick
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