Hello All,
I've finally had a little time to assemble the speaker protection board. I can confirm that the 12volt relays suggested by Prasi do work. Thanks Prasi! I can also confirm that the circuit will work with a straight dc input. In my case I tested it with two 9volt batteries connected in series and the circuit works just fine.
My question to those better at circuit design would be which component would need to be changed to slow down the flash rate of the protection led? It flashes rather quickly. I don't want to change the relay latching time, that is fine. I'm guessing one of the capacitors? Any help would be greatly appreciated.
I've finally had a little time to assemble the speaker protection board. I can confirm that the 12volt relays suggested by Prasi do work. Thanks Prasi! I can also confirm that the circuit will work with a straight dc input. In my case I tested it with two 9volt batteries connected in series and the circuit works just fine.
My question to those better at circuit design would be which component would need to be changed to slow down the flash rate of the protection led? It flashes rather quickly. I don't want to change the relay latching time, that is fine. I'm guessing one of the capacitors? Any help would be greatly appreciated.
Just following up on my question a few weeks back. I too just got around to adding the speaker protection board to my F5 this weekend. Following Prasi's advice as well I connected it directly to my F5 24vdc PSU and it works like a charm. One led lights right away while the other flashes very fast for about 5 sec and then "click", the relays kick in and both leds glow steady. Woohoo!
Thanks Prasi
Hi JSA,
My laptop M-board is burnt
, spilled water. So I can't access my files. But what I remember is c1c2 I changed to 10u to slowdown blinky. But it also leads to longer delay before relay engages. You could try , say, 4.7uf.This is from memory, so I can't be 100%.
May be someone else could suggest.
Reg
Prasi
Hi
I am new to the forum and to the hobby, but I always wanted to built my own amp since I was a kid. So now I started to built a gainclone LM3886 discribed here
A Complete Guide to Design and Build a Hi-Fi LM3886 Amplifier - Circuit Basics
Do I need a DC protection with LM3886 or is such a circuit quasi built into the chip (as it also has mute function)? Would the DC protection board v3 work with my gainclone running at 22v psu (I guess yes as the relays do 24v, but I wanted confirmation before I order the pcbs).
Thx a lot in advance and sorry if the question seems silly to some.
I am new to the forum and to the hobby, but I always wanted to built my own amp since I was a kid. So now I started to built a gainclone LM3886 discribed here
A Complete Guide to Design and Build a Hi-Fi LM3886 Amplifier - Circuit Basics
Do I need a DC protection with LM3886 or is such a circuit quasi built into the chip (as it also has mute function)? Would the DC protection board v3 work with my gainclone running at 22v psu (I guess yes as the relays do 24v, but I wanted confirmation before I order the pcbs).
Thx a lot in advance and sorry if the question seems silly to some.
With great reluctance, I add here a couple of observations on this whole speaker protection/inrush project. It was painful to read nearly 300 posts on this one extremely simple project. 99.9% of the questions have to do with how to solder components, and especially how to check transistor lead configuration. Apparently, most of these people don't know how to use a multimeter and have no idea how to check their work. I do feel sympathetic, but my comments are about the project itself.
Why didn't the authors produce a real "build guide" which answers most of the common questions? You know....look back over 300 comments and you will find at least 150 of them don't know what to do with their transistors.
Perhaps as important would be a circuit description and specifications on performance. At what voltage offset does the protection engage? How long must the offset be present to trigger the protection? Why even bother talking about a 10 second delay, since the circuit will never engage if a dangerous offset is present. Why not include a transformer and rectifier bridge in the main schematics to avoid confusion? Safety warnings and mounting procedures for the inrush limiter should be mandatory.
The protection circuit does not inspire confidence for these reasons. Offset detection is handled by 3 transistors, (2 transistors actually if you consider a single direction offset). The operation of this important circuit depends upon a couple of transistors with unpredictable Beta (luck of the draw). The operation of the circuit will most assuredly change as the pcb warms up inside the amplifier. How and in what direction it will change is unknown, because there isn't enough overall gain to compensate for component variations. Your "unused" relay contact should be grounded, BTW. And the board does not need snubbers or other methods to avoid oscillation.
I can't understand why the whole design relies on a few non-specific parts. One or two op amps (in one chip!) would provide most of the functions. They would be predictable in operation (sufficient gain) and relatively immune to temperature variation (sufficient gain). And.....using a discreet multivibrator circuit? How long has it been since I saw one of those?
So if the authors so desire, a circuit description would assist you and your builders greatly. What are your measured specifications for the design? What was the basis for your design decisions? How about an updated and modernized design using op-amps? Otherwise, we can probably expect to be at post #400 in no time, asking, "Which lead actually IS the collector?"
RA
Why didn't the authors produce a real "build guide" which answers most of the common questions? You know....look back over 300 comments and you will find at least 150 of them don't know what to do with their transistors.
Perhaps as important would be a circuit description and specifications on performance. At what voltage offset does the protection engage? How long must the offset be present to trigger the protection? Why even bother talking about a 10 second delay, since the circuit will never engage if a dangerous offset is present. Why not include a transformer and rectifier bridge in the main schematics to avoid confusion? Safety warnings and mounting procedures for the inrush limiter should be mandatory.
The protection circuit does not inspire confidence for these reasons. Offset detection is handled by 3 transistors, (2 transistors actually if you consider a single direction offset). The operation of this important circuit depends upon a couple of transistors with unpredictable Beta (luck of the draw). The operation of the circuit will most assuredly change as the pcb warms up inside the amplifier. How and in what direction it will change is unknown, because there isn't enough overall gain to compensate for component variations. Your "unused" relay contact should be grounded, BTW. And the board does not need snubbers or other methods to avoid oscillation.
I can't understand why the whole design relies on a few non-specific parts. One or two op amps (in one chip!) would provide most of the functions. They would be predictable in operation (sufficient gain) and relatively immune to temperature variation (sufficient gain). And.....using a discreet multivibrator circuit? How long has it been since I saw one of those?
So if the authors so desire, a circuit description would assist you and your builders greatly. What are your measured specifications for the design? What was the basis for your design decisions? How about an updated and modernized design using op-amps? Otherwise, we can probably expect to be at post #400 in no time, asking, "Which lead actually IS the collector?"
RA
there is a build guide but unfortunately for a previous version of pcb. but the schematic remains same.
here is the link and hope its useful
https://www.google.co.in/url?sa=t&r...x4SYmijI2HTyyj1dQ&sig2=EAGZ5bcUNeDgCoHS2s7Bqw
There are many protection ckts scattered all over DIYA, but unfortunately no PCBs. one such is APEX NE555 opamp protect , but no PCB.
there is also one based on UPA1237 chip, that can do many things including dc detect, delay, fast ac loss switch off and over current...
reg
Prasi
here is the link and hope its useful
https://www.google.co.in/url?sa=t&r...x4SYmijI2HTyyj1dQ&sig2=EAGZ5bcUNeDgCoHS2s7Bqw
There are many protection ckts scattered all over DIYA, but unfortunately no PCBs. one such is APEX NE555 opamp protect , but no PCB.
there is also one based on UPA1237 chip, that can do many things including dc detect, delay, fast ac loss switch off and over current...
reg
Prasi
Last edited:
sorry , was in some hurry i guess, the chip is actually upc1237... here is the datasheet.
http://www.promelec.ru/pdf/upc1237ha.pdf
easy to implement... there are chinese versions of the chip that work well.
Hello
Upon powering up of my speaker protection board I have the following symptoms.
both green and red led's light up and relay K1 engages.
when removing power. Green to off, red flickers to off and K1 disengages,
(24v supply to 2x12 relays, Q1,Q2,Q3,Q5,Q6 are 2n222s').
Hope some one can cast some light on my issues (other than the led of course)
regards
Upon powering up of my speaker protection board I have the following symptoms.
both green and red led's light up and relay K1 engages.
when removing power. Green to off, red flickers to off and K1 disengages,
(24v supply to 2x12 relays, Q1,Q2,Q3,Q5,Q6 are 2n222s').
Hope some one can cast some light on my issues (other than the led of course)
regards
I just installed the these boards over the weekend on my Aleph J amp. Nice boards, the install went pretty quick. I am getting a thump out of the speakers on turn off. I was hoping it would take care of that by switching off the speakers before the amp shuts down. I still get the thump. The boards work and I see the LED blinking when I turn the amp on and then I hear the relays click on. Is this also supposed to work when you turn the amp off? I was hoping it would. I wonder if I did something wrong on the wiring. Is this working for you guys, any help or ideas would be great.
Thanks,
John
Thanks,
John
Hi Kazoo, one of the reasons I purchased the protection boards for my Aleph J was to try to prevent the thump on turn off as well. However, mine behaves in exactly the same way, and the thump still gets through before the contacts open up. I've got my board connected to the dc output of the power supply and my guess is that the residual charge in the capacitors is keeping the protection board powered up for a little bit after the power is turned off. I connected the board this way because I believe I've read that it needs a ground reference to operate the protection circuit properly. I was considering trying to connect it to the power supply board input to see if that would cause the protection circuit to power off quicker. I'm not sure if this is a good idea or not. Maybe one of the others with more experience (AndrewT or Prasi) would be able to help out?
Hi,
Have you observed the lead orientation? Board is made for EBC. I think 2n2222 are cbe. You need to install them opposite to silk.
Also double check your part values.
The ckt should work perfect if built correctly.
A pic of the build would help better.
I do not know if the diya bom has been corrected as the c suffix on the bom part implies center collector, its there in the beginning of this thread posted by 6L6.
Reg
Prasi