Cl-60

You mean for limiting inrush current:

Nope

The CL-60 is a thermally sensitive semiconductor resistors which show a decrease in resistance as temperature increases.

A so called soft-start module doesn't use a thermistor but often relies on a resistor network an relais

Ralph

It's not practical to use resistor for inrush protection on primaries, but if you think about using resistors instead of thermistors in CRC filtering, it's perfectly acceptable.

Peter I have not been following along with a lot of threads lately. What is the Application for CRC filtering?

Anthony

Originally, in Aleph AX, Nelson was using 4 paralleled CL-60 thermistors between capacitors banks (instead of chockes) for PS filtering. I also use those thermistors for filtering and they work pretty well providing additional inrush protection as well. The alternative would be using 0.3-0.5 power resistors instead of chokes or thermistors.

Wow that's a lot of DC current, do they run Hot? What about the reduced ability to handle surge currents due to a small diameter lead?

Anthony

I thought I'd read somewhere that there were some problems with the Thermistor trick as a CRC and here is the link to support is by the One and Only himself:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=8882&highlight=thermistor

Nobody ever reallysolved this althought possible solutions are mentioned


Ralph

They run so hot, that you can't touch them. As to the leads diameter and handling inrush currents, I think that they are still bigger gauge than the fuse element.

Peter Daniel said:

They run so hot, that you can't touch them. As to the leads diameter and handling inrush currents, I think that they are still bigger gauge than the fuse element.

Click to expand...

Point taken, but I do not use fuses after the AC Mains, then it's a ThermoMagnetic Breaker.

Anthony

CL-60 in an AB amp

So...
What about using a CL-60 on the AC side in a Class AB amp?

I have big caps, 61mF - okay, not that big, but big enough I need some inrush protection and I don't want to be bothered with the whole relay delay thing. I'm making a quick 'n' dirty amp.
I figure the caps are big enough to handle the peak draw from the amp, and the only downside could be the additional resistance of the CL-60 when the amp is at idle or low power. Which shouldn't be a problem because the caps are big.
The amp's an ESP P3A, 48VCT transformer, about 34V rails, maybe 80W/ch into 4 ohms.

Thanks for your thoughts...

I don't use fuses on secondaries either, and here few thermistors are used in parallel to avoid current limiting. By comparing them to fuses, I only had in mind the primary circuit.

Re: CL-60 in an AB amp

paulb said:

So...
What about using a CL-60 on the AC side in a Class AB amp?

I have big caps, 61mF - okay, not that big, but big enough I need some inrush protection and I don't want to be bothered with the whole relay delay thing. I'm making a quick 'n' dirty amp.
I figure the caps are big enough to handle the peak draw from the amp, and the only downside could be the additional resistance of the CL-60 when the amp is at idle or low power. Which shouldn't be a problem because the caps are big.
The amp's an ESP P3A, 48VCT transformer, about 34V rails, maybe 80W/ch into 4 ohms.

Thanks for your thoughts...

Click to expand...

It all depends on how much current the amp draws when idle. With little current you may find that voltage drop on thermistor is too big. For comparison, with Alephs it's less than 0.5V.

Peter Daniel said:

I don't use fuses on secondaries either, and here few thermistors are used in parallel to avoid current limiting. By comparing them to fuses, I only had in mind the primary circuit.

Click to expand...

Hey Peter I am trying to find a source for these inductors, they look interesting.

http://www.schottcorp.com/products/...y&cat_id=124&highlight=1&product_number=35070

Anthony

They look interesting. What about ordering samples?

Peter Daniel said:

They look interesting. What about ordering samples?

Click to expand...

Already did, hope to hear from them soon. Digikey has some of thier product for $10 CAD. They do not have the values we would want. I am going to call them tomorrow for an RFQ.

Anthony

Can somebody tell me a proper thermistor that could substitute CL60 and could be ordered from Farnell?

I’m thinking of building an Aleph 3 or 30.

Thanks

The B57234S709M is close to the CL-50. It should work.

voltage drop

I am building an Aleph X with around 25 V rails and total bias of 7 Amps (3.5 amps per side). What kind of drop can I expect on the rails when using CL-60s on primary side of transformer?

About a volt.

What's the best place to put the thermistor?

I'm building a zen v2 with around 35v at the cap (68000uF for now)
I have it installed between the rectifier and the cap right now. Is this the best place, or should I move it to ac primary or secondary?