You need to pass the speaker wire signal into this small pcb of unknow contact quality, and into the small sensor legs. I prefer the non contact solution of the Hall effect sensor. This way the amp signal is not touch by nothing else than the speaker wire you choose...
But this for the info.
SB
But this for the info.
SB
Did a few last changes to my pcb, increase the parts pads size to be easier for DIYer, provision to use an axial input capacitor, instead of the small wima caps, a few silkscreen corrections. It will be 2mm tickness and 2oz copper. If there is interest I may order a few extra, send me an email. Image is from the Gerber viewer, finish won't be Gold ENIG, but rather solder...
Thanks
SB
Thanks
SB
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Also the transfo secondary voltage selection is certainly done by two DPDT relay because there is no way that this simple switch is doing the job, not enough pole, too small rating, etc...
So these relays are probably also powered by the standby power supply...
PCB: Thanks, I'll use a nice 5uF axial input coupling capacitor I have already in stock.
So these relays are probably also powered by the standby power supply...
PCB: Thanks, I'll use a nice 5uF axial input coupling capacitor I have already in stock.
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How do you conclude it's relays and not mosfets? Is there any mention of the amp making a clicking noise upon power on?
No, it will be the original Model One 1 pair at the output...
Analog_sa coming back to the Power-Supply not sure about the use of switching Mosfet for the supply, if the Crowbar is activating that would risk destroying the in series Mosfet? Wouldn't be better to have a closed relay contact instead of the Mosfet in case of Fault?
Anyhow as you mentionned there is probably the need to limit somehow the Crowbar shorting current, just to protect the supply caps. Maybe a ICL like a CL60 in series with the Crowbar? This way, yes Mosfet turning on the caps would survive the Crowbar activation. Any thoughts?
Analog_sa coming back to the Power-Supply not sure about the use of switching Mosfet for the supply, if the Crowbar is activating that would risk destroying the in series Mosfet? Wouldn't be better to have a closed relay contact instead of the Mosfet in case of Fault?
Anyhow as you mentionned there is probably the need to limit somehow the Crowbar shorting current, just to protect the supply caps. Maybe a ICL like a CL60 in series with the Crowbar? This way, yes Mosfet turning on the caps would survive the Crowbar activation. Any thoughts?
Not sure you want an NTC thermistor there. They have a high ohmic resistance at room temperature which drops once they heat up. Perhaps a PTC?
We are discussing a mosfet switch on the primary AC side in series with the fuse, right?
Not quite certain about that, but would think a mosfet with a current rating around 10x that of the fuse should be ok. Seen an fda50n50 used in this spot.
0.5-1.0 Ohm resistor capable of withstanding current impulse of 50-100 Amps for a duration of 100-200ms in case of fuses in rails. To burn single fuse in primary it need to be able to dissipate all the energy from the fully charged rail caps and have thermal switch as a fire hazard precaution if primary fuse didn't blow. As a primary function is a speaker protection nothing should be connected in series with a crowbar
Thanks analog_sa, interesting schematic and indeed on the primary could be a solution... But softstart with relay still possible? I have it in my Pass XA amp clone and the amp still sound gourgeous...
But in the case of the DartZeel, dual mono transfo, and they are supposed to be 300VA on 400VA core, I don<t think that a soft start is needed for smmall 300VA transfo, right?
SB
But in the case of the DartZeel, dual mono transfo, and they are supposed to be 300VA on 400VA core, I don<t think that a soft start is needed for smmall 300VA transfo, right?
SB
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By softstart I meant switching on by using a low current pushbutton. A relay is certainly an option and is pethaps worth comparing the two.
In my clone there is such a soft start. https://aliexpress.ru/item/32814077...earchweb0_0,searchweb201602_,searchweb201603_ но есть и подешевле
What are power transformer VA size, do you know?
I built a Pass amp, 2A bias total, with a 700VA transfo and the only softstart is one CL-60, no relay, nothing, very simple and elegant...
I built a Pass amp, 2A bias total, with a 700VA transfo and the only softstart is one CL-60, no relay, nothing, very simple and elegant...
IMO it is a "must have" when filter caps are bigger that 10mF per rail. as Dartzeel have 10 times that the outcome is obvious.
Even with 10mF and two 300-400W torroidal transformers at least some kind of soft start is highly desirable otherwise rating of fuse in a primary stop making any sense. On a workbench I had blown 5A slow blow fuse with 2x200W torroids (2x55v secondaries) with just 22mF per rail something like 1 out of 20.
What kind of transformer, toroidal? Very simple? - Yes. Working? - 99.5% of the time. Elegant? Single ICL in this place doesn't fit my criteria for elegance 🙂. Circuit in Paroxod4 link way closer to be called elegant.
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