irky

Sounds a touch discouraging ... but I salute your persistence & hope that you get there in the end (& hope you share if you do!!)

Recently got my hands on a scope. My circuit as is has a problem with parasitic oscillation on the virtual ground. To fix this I swapped out the LM324 quad op-amp with a TL074cn. The LM324 cannot sink enough current at it's output to provide a stable virtual ground, the TL074cn seems ok. TL074cn might not be the best chip for the job - it was just what I had in my box - I guess any that can handle 40mA at the output will do. FWIW, this fix didn't have any noticable effect on the functionality! It worked fine with the oscillations (they were at about 1Mhz). Might improve the efficiency a little, but I doubt it as most of the juice is used by the LM386 which doesn't use the virtual ground. cheers Col Thanks for the update. Hmm sustainers, I arrived here thinking there'd be a coherent detailed tutorial for a complete system (nope - just the driver apparently), & it seems the whole genre is still beset with issuettes/quirks, niggles and 'oh so nears'! I'm used to the luxury of confirmed builds (often built by many before I venture that way), so being time 'light' wrt my electronics hobby, I think I'll park this one up & look back in a few years ...there might even be a schematic to accompany the ubiquitous DIY driver coil by then. Cheers.

On the contrary, if someone says something erroneous ...then the associated correction is *very* relevant. BTW I've absolutely no idea what you're going on about ....my response was not in response to the OP's request, but instead your mistake saying the LED doesn't conduct until the forward voltage is breached, here you go... ... yes a spec sheet is essential for establishing the actual parameters are, but clearly you didn't follow your own advice! Now what was all that about jump leads and microphones? (that could be quite useful for singers late for a winter gig due to a flat car battery - they'd have to sing loudly though, LOL).

That's not strictly true.....for example a typical 3mm blue led has a typical 'forward voltage' of between 3.2V & 3.4V....but it still lights up even if you apply as little as 2.9V-3.0V across it (depending on the specific LED) ...albeit way less bright, but by virtue of the fact it's lit means it's conducting! Here's the 1st datasheet I found typing 3mm blue led into goolge... http://www.farnell.com/datasheets/67038.pdf They're quoting a forward voltage of 3.8V, but if you check their graph it conducts from about 3.2V upwards.

Thanks again....actually, since you've now given your coil driver spec - and therefore I have a complete design to build towards - I may well now have a go! I just wanted to build an overall DIY sustainer system to a known confirmed build - but it seems that there's always just a lttle bit missing (& then a lot of grief!) ...I'm surprised that there isn't a complete build package for the whole system (a bit like when you make DIY stompbox). Nevertheless, what you've provided is great - ie nice concise technical info that didn't take me all morning to read - many thanks.

Thank you for such a clear concise explanation Col. If you are a bit unsure of the specs/config of your own driver coil, then I may get unexpected results (so no further forward really) ...but you make some good points nevertheless. ok, if there's no published full diy sustainer design available (driver coil & circuit) & a lot of issues with battery life to do with the simple ones - I think I'll park this one up and wait until someone comes along with "here's a confimed sustainer system, the coil is this spec & this is the the circuit I recommend marries with it"....else I can see this being a big time sump (& spare time is what I don't have) - back to dabbling with stompboxes for now (they normally have confirmed schems, BOMs etc). Thanks once again.

?? no circuit? Ok, Col - do you have a confirmed driver design spec that marrys with your circuit as posted further above? (it looks a little complicated for my first attempt, but I've only a limited amount of time I can spend on this and want to go with a full confirmed design (ie driver coil *and* correctly matched circuit).

Nice location you live there? At the risk of labouring the point, I'm keen to get the parts ordered, but I don't know what to order still .....I'm a little puzzled, earlier in this thread you emphasised that if a new DIY sustainer builder want decent results, then he should stick to your proven design, but your design appears to be only the actual sustainer driver coil? It seems there's a catch22 situation here, ie... begin_loop: "if you want good results you must build to my design". Q: What's your design? A: "here's 50% of what you need" "Hmm, I built a sustainer but I didn't get good results" goto begin_loop Do you see the quandry? As someone said a bit earlier, the sustainer driver coil is only 50% of an overall sustainer system/design ....I'd imagine any system requiring a delicate 'balance' of electrons/magnetic flux, will likely need a well matched circuit (I guess even Fernandes or Sustainiac driver coils would not work too well if mated with other circuits) ...which is why it's probably important to have a complete build/package to work to for someone like me who is new to this ???

So what is the circuit you specifiy to mate with the your driver, so we can all stick to your design? I'm looking forward to getting started...thanks in advance for your help.

Thanks. PSW spoke earlier in the thread of the importance of adhering to his design, to avoid problems (which makes sense). From the chap on the (diyfever) link ... "I decided to go with Fetzer/Ruby amplifier that will drive the sustainer." So does that particular circuit form part of PSW's overall design (eg the 0.2mm coil, coupled with that circuit?) - or as that comment above infers, are the a few options available wrt the final design?

Could psw please confirm one way or the other whether the circuit posted above is part of his overall design that he recommends we stick to? (I need to get the associated parts ordered, but need to be sure of which components to order)

New here (been lurking for a while digesting all the great info - nice forum). Like a good few others (so it seems!), I'd like to have an attempt at making a sustainer....I've read a lot of that huge thread on here (spent way too long in there reading actually - heavy going!) & numerous other related threads on other forums ...but as of yet, I couldn't find the circuit being spoken of ...is the above true (ie that it's not freely available?) or is it tucked away somewhere I've not found yet? I do want to follow your design to the letter (pointless reinventing the wheel!), since I know the driver spec, I just need to marry it up with the correct circuit design ...so can you please post that here? (or link me to it) tks...Irky.