Are you asking about the whole protection & muting circuit, or just the relays? I built a pair of these: Loudspeaker Protection and Muting
but it's not a very easy build for a beginner. The instructions do not include a straightforward BOM, and I spent a lot of time learning about and choosing relays and calculating resistor values. I ended up with Omron Electronics G8P-1C2T-F-DC12. The up side is that by the time you're done you'll have learned a lot about protection & muting circuits!
but it's not a very easy build for a beginner. The instructions do not include a straightforward BOM, and I spent a lot of time learning about and choosing relays and calculating resistor values. I ended up with Omron Electronics G8P-1C2T-F-DC12. The up side is that by the time you're done you'll have learned a lot about protection & muting circuits!
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I looked around and discovered that you need to look very carefully at the specifications for relays. I can't comment on the particular one's you are looking at, but I never found a relay that didn't quickly lose it's ability to break the connection to a speaker when the dc current was high and the load was reactive. The only relay I found that met the needs was the Amplimo. You can buy them direct from Europe. I was going to do this. The reason I did not was because of the shipping costs - they just seemed too high to me and so I didn't buy them out of principle. You may feel differently and want to make the investment in a pair of sturdy Amplimo's.
out put relay
hello Maxpou,
Do you have pcb for that circiut ,? It looks simple enough ,i can sketch my own
Thank Max,
hello Maxpou,
Do you have pcb for that circiut ,? It looks simple enough ,i can sketch my own
Thank Max,
Hi Hophanthiet,
unfortunately I don't have the PCB for the moment I work on that. Maxpou
The Omron G2R-1-E-DC12 is only rated for 8A/30Vdc with an inductive load. Relays like this will only work for small <100W amplifiers, and even then, in a fault scenario, probably only once.
The solid state relays proposed in another recent thread on this topic are a better solution than a typical mechanical relay.
The solid state relays proposed in another recent thread on this topic are a better solution than a typical mechanical relay.
How much power are we talking about here?
I would go to digikey.com, click "Product Index," scroll down to "Relays," select the "Power...." subcategory and start down selecting.
Audio is fairly dainty as far as relay applications go so I wouldn't waste much time thinking hard about it.
If you are concerned about inductive load breaking you can use diodes on the loudspeaker side of the relay to the positive and negative power supply rails.
I would go to digikey.com, click "Product Index," scroll down to "Relays," select the "Power...." subcategory and start down selecting.
Audio is fairly dainty as far as relay applications go so I wouldn't waste much time thinking hard about it.
If you are concerned about inductive load breaking you can use diodes on the loudspeaker side of the relay to the positive and negative power supply rails.
Solid state
Go for a Fet solution .
look at post http://www.diyaudio.com/forums/clas...-irs2092-irfi4020h-200w8r-42.html#post3001459
I received my fets today and do some measurements tomorrow .
The fets cost me $ 4 each and the PIV $ 2.50 , so no major costs .
I couldn't wait and it looks promising , switch on is bad , almost 2 mseconds , so what , no DC or high currents or it wouldn't switch on anyway . But switch off is 80 microseconds at 50 volts DC .
I made some drop in PCB's for a Songle SLA 12 ( not bad either )
I was happy to see a 36 mV drop over the whole PCB that means a "contact resistance of 50 V/8 ohm makes 6.25 amps .0.036 V / 6.25A = 5.76 mOhms !
Looks like SOA is in specs , the graph is a bit rough .
More tomorrow or Sunday .
Cheers ,
Rens
Go for a Fet solution .
look at post http://www.diyaudio.com/forums/clas...-irs2092-irfi4020h-200w8r-42.html#post3001459
I received my fets today and do some measurements tomorrow .
The fets cost me $ 4 each and the PIV $ 2.50 , so no major costs .
I couldn't wait and it looks promising , switch on is bad , almost 2 mseconds , so what , no DC or high currents or it wouldn't switch on anyway . But switch off is 80 microseconds at 50 volts DC .
I made some drop in PCB's for a Songle SLA 12 ( not bad either )
I was happy to see a 36 mV drop over the whole PCB that means a "contact resistance of 50 V/8 ohm makes 6.25 amps .0.036 V / 6.25A = 5.76 mOhms !
Looks like SOA is in specs , the graph is a bit rough .
More tomorrow or Sunday .
Cheers ,
Rens
Speaker relay / on-delay /DC-protection
Hello maxpou,
have a look into the MARANTZ 1200 service manual page 37. There you'll find a simple but perfectly working schematic which I used since years in many power amplifiers (Rotel and Bryston clones). Only a few components are needed. I have a pcb-layout combined with optional soft-start relay available. If interested ask!
Greets
mcfender (RootsAudio)
Hello maxpou,
have a look into the MARANTZ 1200 service manual page 37. There you'll find a simple but perfectly working schematic which I used since years in many power amplifiers (Rotel and Bryston clones). Only a few components are needed. I have a pcb-layout combined with optional soft-start relay available. If interested ask!
Greets
mcfender (RootsAudio)
Attachments
Was this the circuit from QUASI NMOS power amp?, I built this circuit in monoblock and while I was working on a PSU I did a quick check on my built unfortunately I did it in the evening so no power amp included..
It does seem to work fine and the only thing that I had notice was the delay time, it turns on immediately just after the softstart power-on but I guess it could behave differently if a signal from the amp is applied. The relay was a 24v 10 ampere Zettler model. I have here a schematic with an added LED. I just don't know if this will affect the circuit sensitivity. I thought the addition of an indicator LED is more convenient.Anyway am I doing it right? I'm not so sure 'bout the values though...I haven't tried to test the LED.
