Thermistor for Aleph 3 (Inrush current) - Page 2

Nelson Pass · 26th August 2002, 07:57 PM

We use the CL60, which as I recall goes down to 5 ohms
or so inside the warm amplifier, unless it is the AC
line thermistor, in which case it is more like an ohm.

trigon · 26th August 2002, 08:38 PM

Hi.

Mr. NP thank you for the replay. Here is additional info.

CL-60
10 Ohm at no load @ 25C
5 Amp - Max Steady State Current
.18 Ohm - Approx Res @ I max

CL-70
16 Ohm at no load @ 25C
4 Amp - Max Steady State Current
.27 Ohm - Approx Res @ I max

So for this particular Thermistor CL-70 which has 16Ohm resistance and 4A current, I guess if I put 2 in parallel that should drop the resistance even more and increase the current for the regular state.????? Unless I am wrong in my calculations.

Thank you kindly in advance.
Trigon.:headscrat

Nicwix · 26th August 2002, 09:02 PM

Hi

Does the thermister takes a long time to reach steady state conditions, since its resistance depends on case temperature?

Obvious alternate approach is a resistor on the mains side of the transformer bypassed by relay contacts that cut in after say 10 seconds.

Any comments?

Nix

Peter Daniel · 26th August 2002, 09:04 PM

Thermistor gets hot in less than 3 seconds. If you use crappy Chinese bridges, like I do, it is not always a perfect protection.

Nelson Pass · 26th August 2002, 11:25 PM

I use CL60's at 2 to 2.5 amps, and not above, as they
get quite hot. I have seen failures at 4 amps or so, so
above 2 amps I run 1 each on the dual primary windings.

trigon · 26th August 2002, 11:35 PM

Thank you kindly Mr. NP

Trigon.

kirc · 21st October 2002, 11:15 AM

What about using Epcos Inrush Current Limiters ?

Type: B57238S100M000 has 10ohm resistance at 25°C and max current is 5A.

It's usefull for switch-mode power supplies and soft-start motors,..(probably is usefull also for power-up toroid transformer).

Does anyone have some expirience with this thermistors ?

best regards,
Leon

xenofex · 21st October 2002, 05:39 PM

Quote:

Originally posted by Nelson Pass
I use CL60's at 2 to 2.5 amps, and not above, as they
get quite hot. I have seen failures at 4 amps or so, so
above 2 amps I run 1 each on the dual primary windings.

Hi,

I'm plan to use only 2 thermistor CL50 one at primary windings.
of X'former and the other one for the safety ground. Is this going
cause any problem coz the total capacitance value for my Aleph5 power supply is 317mF?

Specs for the thermistor CL50
1. 7 ohms at 25 degrees C ( ambient )
2. Max steady current - 5 Amps

Thanks
cb

Nelson Pass · 21st October 2002, 08:01 PM

It will probably work, but be very hot.

Of course the worst it can do is fail.

Damn! Another dollar down the toilet!

26th August 2002, 09:04 PM	#14
Peter Daniel diyAudio Member Join Date: Jul 2002 Location: Toronto, Canada	Thermistor gets hot in less than 3 seconds. If you use crappy Chinese bridges, like I do, it is not always a perfect protection. __________________ www.audiosector.com “Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC

21st October 2002, 11:15 AM	#17
kirc diyAudio Member Join Date: Aug 2001 Location: Slovenia	What about using Epcos Inrush Current Limiters ? Type: B57238S100M000 has 10ohm resistance at 25°C and max current is 5A. It's usefull for switch-mode power supplies and soft-start motors,..(probably is usefull also for power-up toroid transformer). Does anyone have some expirience with this thermistors ? best regards, Leon __________________ Music is a part of my life, DIY is my life.

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26th August 2002, 07:57 PM	#11
Nelson Pass The one and only Join Date: Mar 2001	We use the CL60, which as I recall goes down to 5 ohms or so inside the warm amplifier, unless it is the AC line thermistor, in which case it is more like an ohm.

26th August 2002, 08:38 PM	#12
trigon diyAudio Member Join Date: May 2002 Location: Canada	Hi. Mr. NP thank you for the replay. Here is additional info. CL-60 10 Ohm at no load @ 25C 5 Amp - Max Steady State Current .18 Ohm - Approx Res @ I max CL-70 16 Ohm at no load @ 25C 4 Amp - Max Steady State Current .27 Ohm - Approx Res @ I max So for this particular Thermistor CL-70 which has 16Ohm resistance and 4A current, I guess if I put 2 in parallel that should drop the resistance even more and increase the current for the regular state.????? Unless I am wrong in my calculations. Thank you kindly in advance. Trigon.:headscrat

26th August 2002, 09:02 PM	#13
Nicwix diyAudio Member Join Date: Dec 2001 Location: Sydney, Australia	Hi Does the thermister takes a long time to reach steady state conditions, since its resistance depends on case temperature? Obvious alternate approach is a resistor on the mains side of the transformer bypassed by relay contacts that cut in after say 10 seconds. Any comments? Nix

26th August 2002, 11:25 PM	#15
Nelson Pass The one and only Join Date: Mar 2001	I use CL60's at 2 to 2.5 amps, and not above, as they get quite hot. I have seen failures at 4 amps or so, so above 2 amps I run 1 each on the dual primary windings.

26th August 2002, 11:35 PM	#16
trigon diyAudio Member Join Date: May 2002 Location: Canada	Thank you kindly Mr. NP Trigon.

21st October 2002, 08:01 PM	#19
Nelson Pass The one and only Join Date: Mar 2001	It will probably work, but be very hot. Of course the worst it can do is fail. Damn! Another dollar down the toilet!

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