jaycee said:
Small-signal transistors suitable for the job will always be available
So, let me get this straight then. Because you fear that 10 years from now there is a chance you can't get a uPC1237, you think it is *better* to built a circuit from discretes today?
That's Ok, but I just thought you really meant *better* in terms of performance.
Jan Didden
janneman said:
Yep, that's it exactly. The only real reason to use the IC is to save board space as you can make a good DC protect circuit with only a few resistors, a capacitor, 4 diodes and 2 transistors
Actually I'm looking at doing it with a resistor (per channel), capacitor, 4 diodes and an optocoupler. I don't know if thats much of an improvement, but I have a load of suitable optos from dead PC PSU's i could use
jaycee said:
The opto is a good idea I hadn't thought of. If you're only using the opto to drive the relay make sure the transistor can handle the voltage it will see when turned off. Seems to me you'd want at least another transistor and a cap for turn on delay.
Does the opto constitute an IC?
I was actually going to use the opto because I wanted to send the DC fault signal to a microcontroller, which would be in control of the speaker relays anyway.
The opto solves the interfacing between amp rail voltages and 5V, and also provides some isolation from digital noise.
Opto's are pretty common again and 4-terminal opto's are probably going to be widely available for some years yet - especially as theyre so commonly used in SMPS.
The opto solves the interfacing between amp rail voltages and 5V, and also provides some isolation from digital noise.
Opto's are pretty common again and 4-terminal opto's are probably going to be widely available for some years yet - especially as theyre so commonly used in SMPS.
uPC 1237HA and soft start
Hi,
my pcb with DC prot.and soft start
Hi,
my pcb with DC prot.and soft start
An externally hosted image should be here but it was not working when we last tested it.
thank u zeonrider Re: uPC 1237HA and soft start
Board looks nice. What was the corner frequency of the filter circuit and total delay time to drop out the relay?
alex mm said:Hi,
my pcb with DC prot.and soft startAn externally hosted image should be here but it was not working when we last tested it.thank u zeonrider
Board looks nice. What was the corner frequency of the filter circuit and total delay time to drop out the relay?
Re: UPC1237/NTE7100
I've built one on a perf board, with external relay. Nice and compact. Seems to work fine at 65V. I was thinking of doing a PCB but if yours is based on the 1237/7100 maybe I could 'lift it' from you.
Are you referring to the NTE7100? Mouser has stock; 100 pc @ $1.44.d3imlay said:
I've built one on a perf board, with external relay. Nice and compact. Seems to work fine at 65V. I was thinking of doing a PCB but if yours is based on the 1237/7100 maybe I could 'lift it' from you.
This is my 1237-based offset protection, switch-on delay as well as amplifier Safe Operation Area protection. This is the unit published by Elektor Electronics in their May issue.
Details at my website.
BTW, I can get 1237's here in Holland for about $1.50 + VAT at 19% if you need help.
Jan Didden
Details at my website.
BTW, I can get 1237's here in Holland for about $1.50 + VAT at 19% if you need help.
Jan Didden
Attachments
Re: Hi!
I'm sorry, I can't freely post the schematic but the complete article is downloadable for 1.20 euro from here:
http://www.elektor.com/magazines/2008/may/protection-system-for-power-amplifiers.427862.lynkx
Jan Didden
zeonrider said:
I'm sorry, I can't freely post the schematic but the complete article is downloadable for 1.20 euro from here:
http://www.elektor.com/magazines/2008/may/protection-system-for-power-amplifiers.427862.lynkx
Jan Didden
Joaquin, this is an english speaking forum. Please provide an English translation if you post in Spanish. Google Translate
I have been using the NTE7100 since last August
So far my speakers have survived a lot of tinkering with MY F5
The SCH I use is similar to the one in post 32
Only thing you may want to consider is same relays designed on purpose for the job.
They must be DC rated as the AC rating of the contacts is meaningless
This is what I use
Loudspeaker relay - toroidal-transformer.com
So far my speakers have survived a lot of tinkering with MY F5
The SCH I use is similar to the one in post 32
Only thing you may want to consider is same relays designed on purpose for the job.
They must be DC rated as the AC rating of the contacts is meaningless
This is what I use
Loudspeaker relay - toroidal-transformer.com
I know this was a long time ago...
... but here we are 4 years later, and I can't find this chip at the two distributors I usually buy from: Farnell and TME.
I had one CA1237HA in a project, it died, now I can't find another one.
I'll try to replace it with a discrete transistor based circuit.
LE:
I'm sure I can find lots of them on ebay, but most of them are fake/poor_quality just like the one that died.
... but here we are 4 years later, and I can't find this chip at the two distributors I usually buy from: Farnell and TME.
I had one CA1237HA in a project, it died, now I can't find another one.
I'll try to replace it with a discrete transistor based circuit.
LE:
I'm sure I can find lots of them on ebay, but most of them are fake/poor_quality just like the one that died.
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