I was never a fan of a relay in the signal path. But you could use the relay to switch output to ground instead, and rely on a rail fuse. If the contacts weld, the drawback is that you'll need a new relay (and perhaps new output transistors) but not new speakers....
Some like to bypass the fuse with a cap.
Some like to bypass the fuse with a cap.
What are you using to power these modules?, by that I mean a separate transformer mounted within the main amp so the modules are powered on when the amp is turned on? or some other way.
My case is very compact, so I don't have room for another Transformer, and probably not even the module itself.
At a push, I could probably run another switched mains lead out of the main amp case to a separate box / case that housed the transformer and module.
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Hmmm, would need to know the total current draw from the relays, to drop from 42v to 24v, and probably quite a hefty resistor to drop the voltage to around 15v or so for the 7812 regulator.
I Might be able to squeeze it in sideways, I'll whip the cover off when I get a minute and see exactly just how much space I have.
Yes, that's what I did. I tend to house things separately for flexibility, I switch everything from a separately housed soft start/power distribution
Yes, that's what I did. I tend to house things separately for flexibility, I switch everything from a separately housed soft start/power distribution
Ordered one from the ebay link, you couldn't buy a single relay for that price
Hi All,
Interesting that there's so much discussion on these modules at the moment.
I built a few of these back in my school days in the form of guitar and P.A. amps for my more musical mates, so have fond memories of them.
Yesterday evening I went to a junk sale at the local radio club and spotted a big box labelled "home made 6 channel audio amp". I have often wondered about toying with active speakers, so it caught my eye. I was encouraged by the fact that I could barely lift it. Seemingly, nobody fancied carrying it to their car so I secured it for a grand total of £5.
Had a quick look when I got home and it contains two huge toroidal mains transformers, 4 33000 uF 63V caps and 6 of these amplifier modules!
So, I'm reading this thread with interest...
Kevin
Interesting that there's so much discussion on these modules at the moment.
I built a few of these back in my school days in the form of guitar and P.A. amps for my more musical mates, so have fond memories of them.
Yesterday evening I went to a junk sale at the local radio club and spotted a big box labelled "home made 6 channel audio amp". I have often wondered about toying with active speakers, so it caught my eye. I was encouraged by the fact that I could barely lift it. Seemingly, nobody fancied carrying it to their car so I secured it for a grand total of £5.
Had a quick look when I got home and it contains two huge toroidal mains transformers, 4 33000 uF 63V caps and 6 of these amplifier modules!
So, I'm reading this thread with interest...
Kevin
and which are totally inappropriate for the original design, just in case anyone is thinking of trying
I wouldn't mind building a pair using the Exicon ECF10N20 and ECF10P20 Fets, just need to source some PCB's, but I don't want to get into the "Etch your own" again", I once had all the gear to do it, but it was quite time consuming and messy.
It would be interesting to see how the Exicons compare to the Hitachi's.
It would be interesting to see how the Exicons compare to the Hitachi's.
The old style boards are big..thing I did not like with this design was, (1) 47k on the tail pair at the emtters.
Even r penfold's book on a high powered100w mosfet amp used a 68k..he also said use heavy duty cable such as cooker type wire!!.
Still I used all 3 types of fets with all good out come.
My mod's did use better current sink at the tail pair plus the use of v limitering in case of short circuit output and let's face it them fet's are pricy.
Even r penfold's book on a high powered100w mosfet amp used a 68k..he also said use heavy duty cable such as cooker type wire!!.
Still I used all 3 types of fets with all good out come.
My mod's did use better current sink at the tail pair plus the use of v limitering in case of short circuit output and let's face it them fet's are pricy.
4 of the modules in mine actually have 10N16s / 10P16s installed, so I should be able to directly compare them.
It might be interesting to design a new PCB with the shortfalls identified in this thread rectified.
Kevin
I totally agree, the amps sound great, but as you mention, some minor tweaks here and there would be a good thing, maybe even redesign the PCB to use SMD devices where possible.
One thing I would like to see addressed is the removal of the Heatsink bracket, and have the transistors mounted directly to the main H/S, I don't think the current heatsink mounting bracket does a very good job of heat transfer.
also, the use of more up to date SMD Driver transistors might make it easier to source parts ... Just a thought as the originals are now obsolete.
But certainly a redesign with all of the problems with the original PCB addressed would be great.
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