Thermistor for Aleph 3 (Inrush current)

[Miles Teg]

Can you give me the species of the thermistors used in Aleph 3, I know how it's works but somme info lake to calculate myself.
TH1 & TH2

 

[Nelson Pass]

We use the Keystone CL60's, Digikey # KC006L-ND

 

[Miles Teg]

Oh! Thanks to Mr Pass for the help. But as I'm French the my best electronic dealer was RadioSpares, so for the Keystone from Digikey, I can't find it. And buy them by internet it's out of subject.

I'm sure that one little explication on the thermistor and there species in Aleph must be most usefull.
Thanks.

 

[cp642]

Miles,

Specs for the thermistor CL60 recomended by mr. pass are as follows

1. 10 ohms at 25 degrees C ( ambient )
2. Max steady current - 5 Amps

You might want to find one of a similar rating. A good brand to start with is Rhopoint, # SG40

cp642

 

[Miles Teg]

Oh well, cp642. You give the temp at 25°. But what is the evolution in temp ? Negative or positive ? (CTN, CTP)

 

[Miles Teg]

Oh sorry ! After reflection it seems to be obvious. I think the impedance must increase with the temperature. I post too fast.

 

[cp642]

as a matter in fact, the impedence decreases with the rise in temp.

 

[Pete Fleming]

Beat me to it

 

[trigon]

Hi.

Can CL-70 be used for Aleph 2.

Thanks.

Trigon.

 

[Salmacis]

How about CL-40 for TH1?

Sorry if this has been beaten to death, but I read the Aleph 2 service manual and got a bit confused about the TH1 which is to operate at 5 Ohm and TH2 (CL-60) which has a 10 Ohm specification.

Now the CL-40 has a 5 Ohm rating, so is it OK to use it for TH1 and CL-60 for TH2?

Thanks, and sorry about my ignorance concerning thermistors

 

[Nelson Pass]

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]

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]

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]

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]

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]

Thank you kindly Mr. NP

Trigon.

 

[kirc]

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]

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]

It will probably work, but be very hot.

Of course the worst it can do is fail.

Damn! Another dollar down the toilet!