A simple protection pcb can be made using a PIC to detect DC and control a relay.
On power up the PIC holds off the relay for 4 seconds.
If the PIC detects DC for more than 500ms it shuts down the relay.
You don't even need an A2D converter as the PIC's input pin threshold is 2 volts.
Just scale two resistors to get the positive phase on one pin and another two resistors to scale the volte on another pin.
I keep seeing large protection pcbs with loads of transistors and op amps when a simple PIC will do the job easily and intelligently.
On power up the PIC holds off the relay for 4 seconds.
If the PIC detects DC for more than 500ms it shuts down the relay.
You don't even need an A2D converter as the PIC's input pin threshold is 2 volts.
Just scale two resistors to get the positive phase on one pin and another two resistors to scale the volte on another pin.
I keep seeing large protection pcbs with loads of transistors and op amps when a simple PIC will do the job easily and intelligently.
Dangerous circuit
Why is this circuit and discussion not prohibited ?
" Certain inherently dangerous topics are not allowed. At this time they include but are not limited to: discussing power supplies directly fed by mains current without a transformer "
This circuit clearly has a line connected power supply with no transformer: Rectifier, filter and voltage regulator for deriving 24VDC.
If allowed, I am seeking more latitude in discussing line connected power supplies
such as Switching power supplies.
Why is this circuit and discussion not prohibited ?
" Certain inherently dangerous topics are not allowed. At this time they include but are not limited to: discussing power supplies directly fed by mains current without a transformer "
This circuit clearly has a line connected power supply with no transformer: Rectifier, filter and voltage regulator for deriving 24VDC.
If allowed, I am seeking more latitude in discussing line connected power supplies
such as Switching power supplies.
Board Finished and ROCKIN' DA HOUSE!
'Twas a very fruitful day!
Finished my first ever amp project, which is Mr. Elliott's P101. Wiring up the diyAUDIO Speaker Protector board was really easy. As I posted on the other forum about the Soft Start board, "It was a piece of cake," even though I've never done anything like this before. All day long I've been thumpin', bumpin', groovin', and grindin'!
Since I'd purchased a Plitron transformer with FOUR secondaries I didn't need another small transformer. Besides the two main secondaries (at 42-volts each) there is one at just under 9 volts and another at 13-volts. I'm using series resistors to step down current a bit on the 13-volts, but one of my electronic genius friends suggests I use a 3-terminal voltage regulator IC. Since he's a veteran engineer with patents I guess I had oughta do what he says.
Thanks to diyAudio boss man, Jason Donald, for his encouraging emails while I was doing this. Look forward to doing business with you again soon.
http://imageshack.us/a/img405/2554/diyaudiospkprotectfinis.jpg
'Twas a very fruitful day!
Finished my first ever amp project, which is Mr. Elliott's P101. Wiring up the diyAUDIO Speaker Protector board was really easy. As I posted on the other forum about the Soft Start board, "It was a piece of cake," even though I've never done anything like this before. All day long I've been thumpin', bumpin', groovin', and grindin'!
Since I'd purchased a Plitron transformer with FOUR secondaries I didn't need another small transformer. Besides the two main secondaries (at 42-volts each) there is one at just under 9 volts and another at 13-volts. I'm using series resistors to step down current a bit on the 13-volts, but one of my electronic genius friends suggests I use a 3-terminal voltage regulator IC. Since he's a veteran engineer with patents I guess I had oughta do what he says.
Thanks to diyAudio boss man, Jason Donald, for his encouraging emails while I was doing this. Look forward to doing business with you again soon.
http://imageshack.us/a/img405/2554/diyaudiospkprotectfinis.jpg
nrg2009, I'd be happy to post the BOM in a day or so when I'm finished with some other chores. I searched like crazy to find compatible stuff and it all is working just fine. The lion's share came from Newark/Element 14.
"How would you test if the speaker protection is actually working? ," is a question that's a cut or 2 above my pay grade. But I'll get an answer shortly from a friend who is a R&D engineer for an international tech firm located in my town. At the moment, all I know is that I hear the relays kick in, and, I get no pops, clicks, or ominous noises from my speakers at turn on.
"How would you test if the speaker protection is actually working? ," is a question that's a cut or 2 above my pay grade. But I'll get an answer shortly from a friend who is a R&D engineer for an international tech firm located in my town. At the moment, all I know is that I hear the relays kick in, and, I get no pops, clicks, or ominous noises from my speakers at turn on.
Hey!
Ok just wondering, would building one of thise protection units be ok for the F5Turbo amplifier ? Iv'e seen on ebay some good protection kits but from what i heard many wont protect over 35watts or so. even tho they may be rated at 30amps. hmm
I was going to ask the same question - seems like we have a similar plan...
Yeah, im building my F5t for a friend and i want his speakers protected! have already built F5 sounds lovely, he insisted on more watts for himself. 25 is ok for me !
Yes, if you find out please let us know
There are a lot of Kits on ebay but i heard someone saying on here that one of the 30Amp ones on there would only work up to around 37w of music.
now maybee i just don't understand it all yet lol
Andrew, does this mean that a DC relay is too weak for the intended purpose of speaker protection?
A relay can be activated with DC or AC.
That is different from breaking a DC or AC load current.
Read the label on your typical relay.
It might say 250Vac 10A and 30Vdc 10A.
Some relays don't even mention the DC rating.
This relay will make and break a load connected to the mains of upto 10A.
But for a DC supply it cannot break more than 30Vdc reliably.
That is different from breaking a DC or AC load current.
Read the label on your typical relay.
It might say 250Vac 10A and 30Vdc 10A.
Some relays don't even mention the DC rating.
This relay will make and break a load connected to the mains of upto 10A.
But for a DC supply it cannot break more than 30Vdc reliably.
Without wanting to get off topic, I would like to answer this. The situation as I understand it: This is something generating income to support the site, we need to be able to support it, and we put our names to the advice given. That's very different to allowing unfettered discussion of AC throughout the forum by anyone who cares to post their unqualified thoughts. There is no conspiracy involved. Opening up the forum to AC discussion and perhaps having it moderated by an insured 3rd party or something complicated like that is certainly an option I'd like to explore in the future - people need good advice and it's not helpful to have to send DIYers elsewhere to get the advice they need. Currently we're just covering our backsides. I agree it's not nearly an ideal situation. So, please consider this an problem that will have a solution found for in in the near future, one way or another.
Just wondering, are we really breaking DC as we are breaking the amp's output ? If so, the DC voltage should be around 1V max when the relais cuts off - or am I missing something ?
Organic1's BOM
As per nrg2009's request, here's BOM for the stuff some folks have been having a hard time tracking down. I'm assuming the rest of the items are fairly boiler plate and easy to find wherever you are.
All these parts came from Newark/Element 14. Let me know if you need any other info.
T1
NPN Transistor
06M7367
T2
NPN Transistor
06M7367
T3
NPN Transistor
06M7367
T4
NPN Transistor
06M7367
T5
NPN Transistor
06M7367
T6
NPN Transistor
06M7407
D1
Switching Diode
06M7433
D2
Zener Diode
06M7371
D3
1A Plastic Silicon Rectifier
10M2938
D4
1A Plastic Silicon Rectifier
10M2938
D5
1A Plastic Silicon Rectifier
10M2938
D6
1A Plastic Silicon Rectifier
10M2938
K1
Standard 5-Pin SPDT Relay
81C8194 (6 volt)
K2
Standard 5-Pin SPDT Relay
81C8194
As per nrg2009's request, here's BOM for the stuff some folks have been having a hard time tracking down. I'm assuming the rest of the items are fairly boiler plate and easy to find wherever you are.
All these parts came from Newark/Element 14. Let me know if you need any other info.
Part
Description
Newark/Element 14 SKU#
NPN Transistor
06M7367
T2
NPN Transistor
06M7367
T3
NPN Transistor
06M7367
T4
NPN Transistor
06M7367
T5
NPN Transistor
06M7367
T6
NPN Transistor
06M7407
D1
Switching Diode
06M7433
D2
Zener Diode
06M7371
D3
1A Plastic Silicon Rectifier
10M2938
D4
1A Plastic Silicon Rectifier
10M2938
D5
1A Plastic Silicon Rectifier
10M2938
D6
1A Plastic Silicon Rectifier
10M2938
K1
Standard 5-Pin SPDT Relay
81C8194 (6 volt)
K2
Standard 5-Pin SPDT Relay
81C8194
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.