Yes, a zener instead of R13 should work. Or you choose R1 and R13 to divide the AC sense voltage by, say, three, e.g R1=33k and R13=10k.
Gentle reminder: the GB for the boards will close in a couple of days. Now is a good time to join it!
Hi Alex, i plan on fitting this circuit to my existing design. However the contraints in the layout suggest that using the amplifier's own regulator to power the comparator will result in the best layout . My question is- will the voltage divider you specified add much noise to the signal or is it negligible? Thanks
Also if i dont need fast turn off, take out everything from R1 to C7?
Also if i dont need fast turn off, take out everything from R1 to C7?
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If you have a split supply on your headphone amp, it may unbalance your rail voltages if the relay is normally operated. No so good.
Sorry @donovas, I am slow this morning. Which divider you're talking about?
The circuit will not add any meaningful noise to the output of the amplifier or the supply rails, which (usually) are low impedance voltage sources. If you're worried about ground currents, leave the GND_CONNECT jumper open, connect signal ground from your amplifier's output to the AMPLIFIER connector, and your power supply ground - to the POWER connector.
If you don't need fast turn off, leave T1 R1 R13 unpopulated. C7 provides a delay when turning on and should always be mounted.
Let me know if I misunderstood your question.
The circuit will not add any meaningful noise to the output of the amplifier or the supply rails, which (usually) are low impedance voltage sources. If you're worried about ground currents, leave the GND_CONNECT jumper open, connect signal ground from your amplifier's output to the AMPLIFIER connector, and your power supply ground - to the POWER connector.
If you don't need fast turn off, leave T1 R1 R13 unpopulated. C7 provides a delay when turning on and should always be mounted.
Let me know if I misunderstood your question.
After the third Omicron group buy closed in June last year, there has been a number of requests for more boards, so I'd like to see if there is interest for another group buy. If interested, please sign up here.
Please excuse my ignorance - and i mean no disrespect.
What advantage would this circuit have over one based on the extremely venerable uPC1237HA?
Granted, you can only get 1237s from chinese vendors these days, so it's less of a commodity part, but it has both DC protection and turn-on delay.
It's generally used in power amps, but reading between the lines of the datasheet, it's a nominal 5v part, tolerant to a bit over 7v. A few years back i designed and successfully used a board with one for headamp use.
What advantage would this circuit have over one based on the extremely venerable uPC1237HA?
Granted, you can only get 1237s from chinese vendors these days, so it's less of a commodity part, but it has both DC protection and turn-on delay.
It's generally used in power amps, but reading between the lines of the datasheet, it's a nominal 5v part, tolerant to a bit over 7v. A few years back i designed and successfully used a board with one for headamp use.
If you have a stash of uPC1237s, figured out how to use them, designed a PCB for them, and that PCB solves your problem, that's all the advantage you need. Learn to use what you have got, and you won't need what you have not.
Everyone else (since you have not made your design available in any form) wishing to use the uPC1237 (or the TA7317P, or any other venerable protection chip) for headphone protection would need to procure the chip(s), figure out how to use them, then design and make a board - all that work for something that is not even a central piece of a build. As you pointed out, these venerable chips are long obsolete (to the extent that NAD replaced the uPC1237 in its products with a pin-compatible discrete module), which is not making this work easier.
For me, the advantage of the Omicron protection is its superb performance (the protection is sensitive, 80mV, and fast, 30mS for a 1V step) achieved with cheap, generic parts, most of which you likely have already, all readily available from many reliable sources. The schematic is publicly available, and the compact (50x50mm), carefully designed PCB that I offer in group buys is inexpensive. It is a simple, convenient, affordable, readily available, tested and proven solution that keeps your, say, $5k Focal Utopias from blowing up when you make a mistake.
Everyone else (since you have not made your design available in any form) wishing to use the uPC1237 (or the TA7317P, or any other venerable protection chip) for headphone protection would need to procure the chip(s), figure out how to use them, then design and make a board - all that work for something that is not even a central piece of a build. As you pointed out, these venerable chips are long obsolete (to the extent that NAD replaced the uPC1237 in its products with a pin-compatible discrete module), which is not making this work easier.
For me, the advantage of the Omicron protection is its superb performance (the protection is sensitive, 80mV, and fast, 30mS for a 1V step) achieved with cheap, generic parts, most of which you likely have already, all readily available from many reliable sources. The schematic is publicly available, and the compact (50x50mm), carefully designed PCB that I offer in group buys is inexpensive. It is a simple, convenient, affordable, readily available, tested and proven solution that keeps your, say, $5k Focal Utopias from blowing up when you make a mistake.
No need to be so defensive, I was legitimately curious.
Unisonic currently manufactures their clone, and they are available in lead-free and halogen-free packages. They don't seem to have much distribution, admittedly, but they are cheap and plentiful on aliexpress.
Unisonic currently manufactures their clone, and they are available in lead-free and halogen-free packages. They don't seem to have much distribution, admittedly, but they are cheap and plentiful on aliexpress.
If you have a suitable uPC1237 headphone protection design, I'd suggest opening a thread on this forum and publishing it. I'm sure people would be interested.
BTW if you know a good source for the TA7317P, let me know. I have a nice speaker protection board board designed for it, but after I got some fakes from Aliexpress, I decided against publishing it. Still using it for my own builds though.
BTW if you know a good source for the TA7317P, let me know. I have a nice speaker protection board board designed for it, but after I got some fakes from Aliexpress, I decided against publishing it. Still using it for my own builds though.
I actually do want to revise my design from a few years ago, but mostly because i want to see if i can safely use one in a high-voltage all-tube headamp, powered by b+. Specifically an Alex Cavalli "Bijou". iirc B+ is over 300v. I am pretty sure that between resistor dividers and zeners i can keep all the pins within their rated voltages. Like i said, the datasheet describes it in terms native to the common solid state power amps of 40 years ago but it seems like a pretty normal low voltage IC with a little effort put into tolerance for voltage spike transients - the 60v power supply rating is directly related to the suggested applications.
I don't have the patience for commerce and would probably just publish schematic, BOM, and gerbers.
I don't have the patience for commerce and would probably just publish schematic, BOM, and gerbers.