T-Bay Posted July 10, 2017 Share Posted July 10, 2017 [quote name='Johnny Wishbone' timestamp='1499712337' post='3333104'] If you go for the Woolly Mammoth, be sure to warn the neighbours first! [/quote] I run a 500w TE stack as my practice amp (on very low to be fair) but in the conservatory and my neighbour is a big music fan and doesn't mind at all - sometimes asks me to turn up! And has been to a couple of our gigs. Quote Link to comment Share on other sites More sharing options...
Johnny Wishbone Posted July 10, 2017 Share Posted July 10, 2017 [quote name='ahpook' timestamp='1499713699' post='3333114'] That's good to hear - I've just ordered a Guma Vintage kit myself and the teeny-tiny transistors were making me worried ! [/quote] I got my kit in October and have only just braved it! They are tiny but with a magnifier, pair of tweezers and pointed soldering bit it was a 2 minute job! The hints in the instructions are very helpful. Quote Link to comment Share on other sites More sharing options...
ahpook Posted July 11, 2017 Share Posted July 11, 2017 [quote name='Johnny Wishbone' timestamp='1499719309' post='3333174'] I got my kit in October and have only just braved it! They are tiny but with a magnifier, pair of tweezers and pointed soldering bit it was a 2 minute job! The hints in the instructions are very helpful. [/quote] Thanks for the tip (ahem) - I'm concerned about the SMT J201s and their susceptibility to static...did you earth yourself up ? Quote Link to comment Share on other sites More sharing options...
Johnny Wishbone Posted July 11, 2017 Share Posted July 11, 2017 (edited) [quote name='ahpook' timestamp='1499763830' post='3333369'] Thanks for the tip (ahem) - I'm concerned about the SMT J201s and their susceptibility to static...did you earth yourself up ? [/quote] No, the only precaution I took was to leave them in their sealed pack until I was ready to tackle them. I still managed to drop one on the carpet all the same! Edited July 11, 2017 by Johnny Wishbone Quote Link to comment Share on other sites More sharing options...
ahpook Posted July 11, 2017 Share Posted July 11, 2017 [quote name='Johnny Wishbone' timestamp='1499765140' post='3333378'] No, the only precaution I took was to leave them in their sealed pack until I was ready to tackle them. I still managed to drop one on the carpet all the same! [/quote] OK, my plans for sheets of tin foil, wire and various croc clips might be a bit OTT then ! Quote Link to comment Share on other sites More sharing options...
bobbass4k Posted July 11, 2017 Share Posted July 11, 2017 I work with smt pretty much every day, I've never actually seen an smt part (or any part actually) killed by static. ESD precautions are generally overzealous, and with good reason, but handling them with esd tweezers and just not licking them or rubbing them on the dog will usually be more than adequate. Quote Link to comment Share on other sites More sharing options...
rmorris Posted July 11, 2017 Share Posted July 11, 2017 [quote name='bobbass4k' timestamp='1499769337' post='3333425'] I work with smt pretty much every day, I've never actually seen an smt part (or any part actually) killed by static. ESD precautions are generally overzealous, and with good reason, but handling them with esd tweezers and just not licking them or rubbing them on the dog will usually be more than adequate. [/quote] +1 Same here. Not saying it can't happen - and it may be more likely that an ESD hit could cause damage that causes a failure further down the line - 6 months ? 6 years ? But unless you are experiency static shocks it's pretty safe for a DIY effort. Guess I'll wandr back to the lab area now and Zap! some CMOS logic Quote Link to comment Share on other sites More sharing options...
Johnny Wishbone Posted July 12, 2017 Share Posted July 12, 2017 (edited) Guys, I've hit a brick wall in my search for wiring guidance on a bypass looper that I (foolishly, it appears) believed would be straightforward. Hopefully the collective wisdom of some experienced builders might be able to assist. I'm wanting to build the following: a passive bypass looper with two loops in series, that has two footswitches. One footswitch selects loop A OR loop B, whilst the other selects both loops together (A+B ). Bright Onion sells such a device, but (a) it also has a master bypass, which i don't require, and (b ) I could build it myself for considerably less outlay. With the exception of the aforementioned, I only seem to be able to find diagrams that do either A/B looping with master bypass, or just 2 series loops each with their own bypass. I dont really want to have to do the old "sideways foot operating 2 switches at once" dance, and what I want is obviously possible as it's been done. Can anyone devise a method for wiring what I'm trying to achieve? Edited July 12, 2017 by Johnny Wishbone Quote Link to comment Share on other sites More sharing options...
2 left thumbs Posted July 13, 2017 Share Posted July 13, 2017 well i certainly wouldn't call myself experienced, and i'm not sure if this is wisdom or total nonsense. loop a input jack to "on side" of switch 1 loop b input jack to "off side" of switch 1 connect both output sides of switch 1 to "on side" of switch 2 connect loop a + b jacks to "off side" of switch 2 connect switch 2 outputs to output jack hope that makes sense Quote Link to comment Share on other sites More sharing options...
2 left thumbs Posted July 13, 2017 Share Posted July 13, 2017 for anyone thinking of doing a first build i can't recommend fuzz dogs pedal parts strongly enough yes you have to do a bit of thinking but with the instructions and the pcb's don't rush it even a total novice like me can end up with fully functioning pedals 1 blueberry boutique version and 1 exotic bb no pictures yet, the blueberry got left naked and the bb well i experimented, could have been better but it will do Quote Link to comment Share on other sites More sharing options...
ahpook Posted July 18, 2017 Share Posted July 18, 2017 Need a bit of advice folks ! I've started building the GUMA Vinatge kit ans have, with as much care as my shaky hands and bad eyes will allow, soldered the SMT JFETs in. I've quickly checked the Gate - Source and Gate - Drain resistances and although I was expecting an open circuit, both chips are reading ~250K ohm. Any idea if I've trashed the chips ? Quote Link to comment Share on other sites More sharing options...
rmorris Posted July 19, 2017 Share Posted July 19, 2017 [quote name='ahpook' timestamp='1500369590' post='3337207'] Need a bit of advice folks ! I've started building the GUMA Vinatge kit ans have, with as much care as my shaky hands and bad eyes will allow, soldered the SMT JFETs in. I've quickly checked the Gate - Source and Gate - Drain resistances and although I was expecting an open circuit, both chips are reading ~250K ohm. Any idea if I've trashed the chips ? [/quote] Are the 250K readings with the JFets in the circuit ? Quote Link to comment Share on other sites More sharing options...
ahpook Posted July 19, 2017 Share Posted July 19, 2017 [quote name='rmorris' timestamp='1500454186' post='3337811'] Are the 250K readings with the JFets in the circuit ? [/quote] That's all that's soldered in at the moment - I've measured the voltage drops as suggested by Julian at Schalltechnik (very helpful chap) and I get 0.7 Gate - Drain/Source and 1.3 D-S/S-D The D-S/S-D are a volt higher than they should be so I suspect that I've overheated the transistors. Quote Link to comment Share on other sites More sharing options...
bobbass4k Posted July 19, 2017 Share Posted July 19, 2017 [quote name='ahpook' timestamp='1500454580' post='3337819'] That's all that's soldered in at the moment - I've measured the voltage drops as suggested by Julian at Schalltechnik (very helpful chap) and I get 0.7 Gate - Drain/Source and 1.3 D-S/S-D The D-S/S-D are a volt higher than they should be so I suspect that I've overheated the transistors. [/quote] How are you measuring the D-S voltage drop? It isn't as simple as it is for the, G-D/S, internal capacitance can skew the readings. Try shorting source and gate and check the reading again, 1.3 sounds about right to me, as long as it's not fully short or open its probably fine. Like static, it's actually pretty hard to kill a part with heat. I'm not sure where this perception of smt parts as delicate faberge eggs comes from, but it's really not true. Quote Link to comment Share on other sites More sharing options...
ahpook Posted July 19, 2017 Share Posted July 19, 2017 [quote name='bobbass4k' timestamp='1500461154' post='3337920'] How are you measuring the D-S voltage drop? It isn't as simple as it is for the, G-D/S, internal capacitance can skew the readings. Try shorting source and gate and check the reading again, 1.3 sounds about right to me, as long as it's not fully short or open its probably fine. Like static, it's actually pretty hard to kill a part with heat. I'm not sure where this perception of smt parts as delicate faberge eggs comes from, but it's really not true. [/quote] I'm using the diode mode on my DMM. Thanks for the reassurace - this is my first time working with SMD and it's a proper pain with my far-from-prefect eyesight. Thanks for the tip about shorting the S-G connections - I'll give that a whirl. Quote Link to comment Share on other sites More sharing options...
rmorris Posted July 19, 2017 Share Posted July 19, 2017 (edited) [quote name='bobbass4k' timestamp='1500461154' post='3337920'] How are you measuring the D-S voltage drop? It isn't as simple as it is for the, G-D/S, internal capacitance can skew the readings. Try shorting source and gate and check the reading again, 1.3 sounds about right to me, as long as it's not fully short or open its probably fine. Like static, it's actually pretty hard to kill a part with heat. I'm not sure where this perception of smt parts as delicate faberge eggs comes from, but it's really not true. [/quote] +1 Sounds about right to me too. And semiconductors - SMT or Thru Hole - are fairly robust when it comes to soldering. Of course, it helps if you use a temp controlled iron and nice and hot so that iron only needs a short contact time with the component leg - especially if using Lead Free solder. Edited July 19, 2017 by rmorris Quote Link to comment Share on other sites More sharing options...
ahpook Posted July 19, 2017 Share Posted July 19, 2017 [quote name='bobbass4k' timestamp='1500461154' post='3337920'] How are you measuring the D-S voltage drop? It isn't as simple as it is for the, G-D/S, internal capacitance can skew the readings. Try shorting source and gate and check the reading again, 1.3 sounds about right to me, as long as it's not fully short or open its probably fine. Like static, it's actually pretty hard to kill a part with heat. I'm not sure where this perception of smt parts as delicate faberge eggs comes from, but it's really not true. [/quote] OK, after shorting the G-S the voltage drop is still about the same. Right then, I reckon that means things aren't as bad as I first thought. Quote Link to comment Share on other sites More sharing options...
rmorris Posted July 19, 2017 Share Posted July 19, 2017 [quote name='ahpook' timestamp='1500463880' post='3337958'] OK, after shorting the G-S the voltage drop is still about the same. Right then, I reckon that means things aren't as bad as I first thought. [/quote] Yep - I don't think there's a problem. As Bobbass said failure usually open or short circuit - not intermediate value. What is the jfet model number ? Quote Link to comment Share on other sites More sharing options...
ahpook Posted July 19, 2017 Share Posted July 19, 2017 [quote name='rmorris' timestamp='1500471383' post='3338058'] Yep - I don't think there's a problem. As Bobbass said failure usually open or short circuit - not intermediate value. What is the jfet model number ? [/quote] Cool They're MMBF-J201s Quote Link to comment Share on other sites More sharing options...
rmorris Posted July 19, 2017 Share Posted July 19, 2017 [quote name='ahpook' timestamp='1500471646' post='3338062'] Cool They're MMBF-J201s [/quote] Okay. Just checking that if there were something wrong they'd be easy enough to replace without having to get another kit of parts. That series of jfet not so common in UK (to avoid shipping charges out of scale with the cost of a few small components) but Farnell have stock atm so should should be okay. And your build is probably okay anyway. Good Luck... Quote Link to comment Share on other sites More sharing options...
ahpook Posted July 19, 2017 Share Posted July 19, 2017 [quote name='rmorris' timestamp='1500475993' post='3338106'] Okay. Just checking that if there were something wrong they'd be easy enough to replace without having to get another kit of parts. That series of jfet not so common in UK (to avoid shipping charges out of scale with the cost of a few small components) but Farnell have stock atm so should should be okay. And your build is probably okay anyway. Good Luck... [/quote] That sounds right as the kit's from a German company. I'll press on now, reassured by all the helpful advice. Many thanks everyone. Quote Link to comment Share on other sites More sharing options...
bobbass4k Posted July 20, 2017 Share Posted July 20, 2017 If you do have any issues with them let me know, I've got a big strip in the transistors drawer, I'd be happy to drop a few in an envelope (and an ESD bag of course...). I think you'll be fine though, before bitsbox started selling adapter boards for the SOT-23s I just used to solder leads then blob them in epoxy to use them as through-hole substitues... That was definitely not a graceful solution, but they all worked. Quote Link to comment Share on other sites More sharing options...
ahpook Posted July 20, 2017 Share Posted July 20, 2017 (edited) [quote name='bobbass4k' timestamp='1500553282' post='3338653'] If you do have any issues with them let me know.... [/quote] That's a very kind offer, but I assembled the kit this afternoon (about 4 hours all told I reckon) and it works a treat ! It is an excellent kit - really easy to put together once the SMD sweats were over. Sound-wise I'm blown away - very much to my taste indeed. There an optional SMD chip you can fit in place of the DIL Opamp which is meant to be less noisy and fatter sounding. That's a nice bit of practice soldering for me ! Edited July 20, 2017 by ahpook Quote Link to comment Share on other sites More sharing options...
Bigwan Posted July 20, 2017 Share Posted July 20, 2017 The Guma and Antique are excellent kits. I'm almost finished the Pumpernickel compressor. It's slightly more awkward, but still good. Quote Link to comment Share on other sites More sharing options...
T-Bay Posted August 2, 2017 Share Posted August 2, 2017 I have been busy with a few things so didn't get around to ordering stuff until today. I now have a woolly mammoth clone kit plus assorted bits on its way to me. I can't wait to have a play and see how it works out. It's been ages since I have done anything more than just replace bits or do a simple rewire. Quote Link to comment Share on other sites More sharing options...
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