problem
Hi
I'm having some problems with this board.
I've attempted to build the board, first attempted at powering with 12 dc. both LED's lit immediately and stayed lit, unblinking. I checked my 945transistors and indeed i had accidentally brought c versions, so I soldered them and swapped the leg placement.
Next attempt at powering on the same result happens both LED's lit immediately unblinking.
I've checked polarity of capacitors and diodes and all seems fine to me.
Resistors all seem ok.
I'm at a lose to what i've done wrong! any help would be great!!!
Thanks
Hi
I'm having some problems with this board.
I've attempted to build the board, first attempted at powering with 12 dc. both LED's lit immediately and stayed lit, unblinking. I checked my 945transistors and indeed i had accidentally brought c versions, so I soldered them and swapped the leg placement.
Next attempt at powering on the same result happens both LED's lit immediately unblinking.
I've checked polarity of capacitors and diodes and all seems fine to me.
Resistors all seem ok.
I'm at a lose to what i've done wrong! any help would be great!!!
Thanks
An externally hosted image should be here but it was not working when we last tested it.
Attachments
I am also confused with what to do with the power supply to the board. I have a transformer with 2x12 VAC windings that i will be wiring in series to get 24VAC out. Question is, do I leave the two wires forming the series connection floating or do I connect them to main PSU ground or something similar?
Thanks
Thanks
transistor legs seem to be touching each other. Just check if there are any shorts. Also does the LED blink very quickly, which looks as if its continuously on?? whats the value of C3?
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I'm also having a few problems working out how to integrate this into my build.
I'd like to use it with a HoneyBadger build, which is using a 50-0-50 transformer for the PSU (giving an output DC of ~76V) - this works fine, just giving some background.
Due to the high supply voltage, I've elected to use a secondary transformer (a 12-0-12 w/windings configured for 24v). I've got 24v relays, and using a separate bench/lab power supply of 34V, I can get the speaker protect board to operate.
My queries are with respect to the aux transformer. Does it need to be wired in a certain way with respect to the main PSU ground? Or does the DC offset detection come from comparing the two spk inputs on the board?
I realize that the voltage rating for this supply is beyond what could be relied upon for protecting the speakers - I've decided to essentially use the board for on/off muting until I have time to investigate rugged enough protection for the badger..
I did try using a winding @ 50V to supply the board, however R14 began to get too hot (and smokey!). I was hesitant to simply up the power rating of the resistor - has anyone got any tips or examples of using this board at higher voltages?
TBH I've found that whilst there is a lot of information on the forums regarding this project, much of it seemed a bit contradictory and has left me somewhat confused..
I'd like to use it with a HoneyBadger build, which is using a 50-0-50 transformer for the PSU (giving an output DC of ~76V) - this works fine, just giving some background.
Due to the high supply voltage, I've elected to use a secondary transformer (a 12-0-12 w/windings configured for 24v). I've got 24v relays, and using a separate bench/lab power supply of 34V, I can get the speaker protect board to operate.
My queries are with respect to the aux transformer. Does it need to be wired in a certain way with respect to the main PSU ground? Or does the DC offset detection come from comparing the two spk inputs on the board?
I realize that the voltage rating for this supply is beyond what could be relied upon for protecting the speakers - I've decided to essentially use the board for on/off muting until I have time to investigate rugged enough protection for the badger..
I did try using a winding @ 50V to supply the board, however R14 began to get too hot (and smokey!). I was hesitant to simply up the power rating of the resistor - has anyone got any tips or examples of using this board at higher voltages?
TBH I've found that whilst there is a lot of information on the forums regarding this project, much of it seemed a bit contradictory and has left me somewhat confused..
A Zener in the line from +76Vdc to your aux supply would drop lots of voltage.
They don't mind being run hot for extended periods.
A 500mW 15V Zener will pass 33mA at max rating. You could probably pass 25mA permanently without any reliability issues.
A pair would drop 30V. Then regulate down to your required 24Vdc or 30Vdc (for a 24V relay) using an LM317.
If you need much more current, then a string of 1W 10V Zeners could pass 80 to 90mA.
They don't mind being run hot for extended periods.
A 500mW 15V Zener will pass 33mA at max rating. You could probably pass 25mA permanently without any reliability issues.
A pair would drop 30V. Then regulate down to your required 24Vdc or 30Vdc (for a 24V relay) using an LM317.
If you need much more current, then a string of 1W 10V Zeners could pass 80 to 90mA.
Hi
So an update with mine,
I replaced the transistors, with ones with right pin layout ones but different types, just what i could get easy here in the UK from RS components;
Fairchild KSP2222ABU NPN Bipolar Transistor, 600 mA, 40 V, 3-Pin TO-92
Fairchild BC33740BU NPN Bipolar Transistor, 800 mA, 50 V, 3-Pin TO-92
I also replaced relays with 5v ones;
RS stock number 93-3768
It now works but takes about 10seconds to latch. I guess that's because I'm using different transistors?
Interestingly for me (I'm fairly un-experienced with this type of electronics) when I first tried it with the new relays and transistors at 12v with my bench PS, it didn't work it only started to work when I increased the voltage to around 15v and would engage in about 4-5 secs. I measured the voltage across the relays as around 7v. After turning it on and off maybe 20 times and changing the voltages I noticed it was starting to work at 12v , sometimes it would sometimes it wouldn't. In the end it seems to be consistently working now in everyday use
Any idea's what caused this behavior? could it be from using the capacitors before at 24v with the other relays?
So an update with mine,
I replaced the transistors, with ones with right pin layout ones but different types, just what i could get easy here in the UK from RS components;
Fairchild KSP2222ABU NPN Bipolar Transistor, 600 mA, 40 V, 3-Pin TO-92
Fairchild BC33740BU NPN Bipolar Transistor, 800 mA, 50 V, 3-Pin TO-92
I also replaced relays with 5v ones;
RS stock number 93-3768
It now works but takes about 10seconds to latch. I guess that's because I'm using different transistors?
Interestingly for me (I'm fairly un-experienced with this type of electronics) when I first tried it with the new relays and transistors at 12v with my bench PS, it didn't work it only started to work when I increased the voltage to around 15v and would engage in about 4-5 secs. I measured the voltage across the relays as around 7v. After turning it on and off maybe 20 times and changing the voltages I noticed it was starting to work at 12v , sometimes it would sometimes it wouldn't. In the end it seems to be consistently working now in everyday use
Any idea's what caused this behavior? could it be from using the capacitors before at 24v with the other relays?
Thanks Andrew - I had thought about doing this (the zener method) a while back, but it slipped my mind, fortunately you reminded me
. I did a quick simulation and it looks good, more testing to be done, but I'm happy that it will work in the end.For those who might stumble on to this in future and are unsure how to proceed, have a look at this page by Rod Elliott:
Pre-Regulator, this is basically what I've decided to do, and he explains and provides examples much better than I can
Used with a low voltage/power headphone amplifier
Hi,
Will this design work properly when used with a low power/voltage headphone amplifier such as the 12 volt driven 'NP-100v12: 12AU7 (ECC82) / IRF510 Headphone Amp' by Rogers Gomez to get rid of the enormous pop during power on and off?
Best regards,
Lars
Hi,
Will this design work properly when used with a low power/voltage headphone amplifier such as the 12 volt driven 'NP-100v12: 12AU7 (ECC82) / IRF510 Headphone Amp' by Rogers Gomez to get rid of the enormous pop during power on and off?
Best regards,
Lars
Hi
Everything on my F5 / Soft start/ Protection board are done/connected - seems fine.
Powered up with no signal or loudspeakers connected.
But when I meassure spk1 and spk2 out on the protection board, they are shorted/connected (my dmm tester beep) - testing for shorts.
Isnt that a problem?
Baek47
Everything on my F5 / Soft start/ Protection board are done/connected - seems fine.
Powered up with no signal or loudspeakers connected.
But when I meassure spk1 and spk2 out on the protection board, they are shorted/connected (my dmm tester beep) - testing for shorts.
Isnt that a problem?
Baek47
My multimeter beeps up until a few tens of ohms. I would think the output impedance of your amp would be very very low so will appear to be shorted .
If you have a bench supply, try testing the protection board and see how it works and what conditions trip it.
This also reassure that it's working.
I think if something was wrong you would see an open circuit eg infinite resistance because the board has disconnected the amp.
Assuming you've setup the bias I would check the output for DC (whichmay be part of the bias setup. It is for my f4) and if there's no offset try hooking it up to some speakers and then turn it up slowly.
If you have a bench supply, try testing the protection board and see how it works and what conditions trip it.
This also reassure that it's working.
I think if something was wrong you would see an open circuit eg infinite resistance because the board has disconnected the amp.
Assuming you've setup the bias I would check the output for DC (whichmay be part of the bias setup. It is for my f4) and if there's no offset try hooking it up to some speakers and then turn it up slowly.
I don't see why not, with the appropriate relays; maybe 5v, but I'll let others chime in to confirm. When you say it's 12V driven, that uses a 12v transformer? (I'm not familiar with the amp in question).