speaker protection circuit

bigpanda · 16th May 2005, 05:04 PM

Find this protection circuit:

http://users.otenet.gr/~athsam/protection_2_EN.htm

and like to try on it. The kyt81-122 is difficult to find so can I use a ntc thermo resistor instead. I would think of feeding R3,R2 into - input of IC1a and R1,ntc into + input of IC1a. Would that work? How are we going to test if this part works? If I am going to glue the sensor to a test heatsink and do the calibration or testing, I might never able taking it off and glue it to the working one? Can I use a pot for R3 so as to adjust the temperature for cut-off.

moamps · 17th May 2005, 07:58 PM

Quote:

Originally posted by bigpanda
The kyt81-122 is difficult to find so can I use a ntc thermo resistor instead. I would think of feeding R3,R2 into - input of IC1a and R1,ntc into + input of IC1a. Would that work?

Hi,
Yes.

Quote:

How are we going to test if this part works?

With cheap thermometer or with your fingers.

Bolt NTC on a small sheet of metal on one side. Use your soldering iron and warm up the opposite side. Put your finger on the NTC. Lift your finger up when the NTC gets too hot for you; this means that the the temperature is about 65-70C. Immediately measure NTC resistance. Use the same value for R3. Simple, right?

Quote:

If I am going to glue the sensor to a test heatsink and do the calibration or testing, I might never able taking it off and glue it to the working one?

I wouldn't be in favor of this. A better idea is to use a small piece of metal bolt and a screw. Use thermal grease between the heatsink and NTC.

Quote:

Can I use a pot for R3 so as to adjust the temperature for cut-off.

Yes.

Regards,
Milan

bigpanda · 20th May 2005, 04:46 PM

Tks Milan,

If I still can't get the kyt81-122 by end of this month, I should try using the ntc thermo-resistor.

mayky · 6th June 2005, 01:38 PM

Look the uPC1237H IC datasheet.

www.alldatasheet.com

bigpanda · 10th June 2005, 06:31 AM

Tks mayky,

Any schematic for a complete project with the uPC1237H?

mayky · 10th June 2005, 05:42 PM

I find this IC in Rotel RB-1090 schematic.

You can find this here: http://www.eserviceinfo.com

Mayky

ajithkumarv · 3rd November 2009, 09:41 AM

Did you tried this?.. is it working?

16th May 2005, 05:04 PM	#1
bigpanda diyAudio Member Join Date: Jun 2004 Location: HKSAR	speaker protection circuit Find this protection circuit: http://users.otenet.gr/~athsam/protection_2_EN.htm and like to try on it. The kyt81-122 is difficult to find so can I use a ntc thermo resistor instead. I would think of feeding R3,R2 into - input of IC1a and R1,ntc into + input of IC1a. Would that work? How are we going to test if this part works? If I am going to glue the sensor to a test heatsink and do the calibration or testing, I might never able taking it off and glue it to the working one? Can I use a pot for R3 so as to adjust the temperature for cut-off.

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20th May 2005, 04:46 PM	#3
bigpanda diyAudio Member Join Date: Jun 2004 Location: HKSAR	Tks Milan, If I still can't get the kyt81-122 by end of this month, I should try using the ntc thermo-resistor.

6th June 2005, 01:38 PM	#4
mayky diyAudio Member Join Date: Mar 2005 Location: Mohács	Look the uPC1237H IC datasheet. www.alldatasheet.com

10th June 2005, 06:31 AM	#5
bigpanda diyAudio Member Join Date: Jun 2004 Location: HKSAR	Tks mayky, Any schematic for a complete project with the uPC1237H?

10th June 2005, 05:42 PM	#6
mayky diyAudio Member Join Date: Mar 2005 Location: Mohács	I find this IC in Rotel RB-1090 schematic. You can find this here: http://www.eserviceinfo.com Mayky

3rd November 2009, 09:41 AM	#7
ajithkumarv diyAudio Member Join Date: Oct 2009	Did you tried this?.. is it working?