Another contribution by Chris. This time he made some improvements and addons on a rare and wild Death by Audio circuit. Tone houndz...stay away!
Chris says:
I don't know if this warrants its own post but I wanted
to show it to you anyway since I was the one who verified your purple
card drawing.
Since I built
that up I wasn't happy with the bleed through in bypass that sometimes
happens with the LM567. So I used the old "millennium bypass" trick of
adding a mosfet to handle the LED switching so that you can use only a
DPDT for true bypass with an indicator light. THEN I used the now-vacant
set of poles on a 3PDT to connect/disconnect the power supply to the
LM567 when the circuit is bypassed. So NO NOISE! I also added the master
volume, because if ANY circuit needs it, it is this loud beast. Then I
put the frequency pot (which I cut down to 10k) on a switched expression
jack so that you can get foot-controlled crazy pitch-wah sounds with a
standard TRS expression pedal like an inexpensive m-audio or nektar
controller. Anything more than 15-20k of resistance for the frequency
control just takes you into slower and slower chopped/tremolo territory.
And the 10k pot still allows for some of that in the toe up/CCW
position and all of the pitch control as you turn the knob up/put the
treadle down.
I added a toggle to change the resistance on the frequency sweep - this
allows for a low range and high range mode on the frequency. Since most
expression pedals have 10k pots, I wanted to keep the frequency pot at
10k too so that the sweep matches whether you are using the knob or an
exp pedal.
I've never heard of this bypass before. I have a project that needs this very solution. But if I'm looking at this right, don't you need a second diode from gate to ground?
ReplyDeletehttp://www.geofex.com/article_folders/millenium/milckt3.gif
I just used the tagboard blog layout, which was posted about 10 years ago, I think - it is just a DPDT, a mosfet, a single diode, an LED and a CLR.
DeleteWow, super nice mods.. would it be possible, for you or Chris to share this schematic ! Cheers
DeleteI actually do not have a schematic for this one. Anders drew one from a trace he did of one of the purple business card PCBs. All my mods were done from his drawing.
DeleteJust boxed one up and everything is working as expected. Built the original purple business card layout as well and the mods really kick it up a notch.
ReplyDeleteDon't know if I messed something up or if it's the layout, but my potis are all working the wrong way. As it's all about noise it doesn't matter anyway. Justr wanted to mention it.
The expression-input is really useful and makes this beast actually kind of playable. Choppy tremolo, squeaking ringmod-sounds or a totally messed up wah. It's all in there. Thanks alot! :)
I'm so stoked to hear that you dig the mods I came up with for this all ready bonkers circuit! As far as the pots working in reverse - I don't know what to tell you as I've built 3-4 of these for friends and the gain and volume get louder as you turn them clockwise, and the frequency pitch goes up when you turn it in that direction as well... I'm not worried about it if you aren't, tho.
DeletePretty sure I messed up the lug-numbering. But nothing to worry bout. :)
DeleteHi guys! First time here but I already love this blog
ReplyDeleteFinished last nite this little trouble kid. Everything works as expected, the only thing that Is the led light always on....is it supposed to be like that?? The led is wired only onboard at the spots led+ led-.......I was supposed to wire one leg on the 3dpt??
The LED is supposed to switch on and off with the effect. I would check the pinout of the mosfet and the polarity of the diode - I simply integrated the old "millennium bypass" layout with this board so that switching + LED on/off could be handled with only 6 lugs.
DeleteThe diode seems correct and the MOSFET too....In the while my master volume pot made some smoke....uff....it needs some careful inspection
ReplyDeletehello, i think i draw the schematic of the board... can i send it to you and maybe draw over the mods?
ReplyDeleteYes please
ReplyDeleteThe smoke from your level pot sounds like you have something shorting the power supply to pad 3 of that pot. I would check all your cuts and copper strips on the underside of the board for bridges. Stripboard building can really test your patience - but I can confirm that the above layout works as I have built several of these.
DeleteI think I got some metal particles inside the pot..(I used one of those for board mounting so I cut partially the lugs and drilled holes for the wires)..but apart from that and the led that stays always on I would say it works...just like on the demo.
ReplyDeleteI have still some oscillation when I don't play but I heard that also on the demo....I mean if the diode or MOSFET orientation were wrong I don't think it would work at all....no?
I used an LM567C and most of the important parts from Banzai....they are quite reliable
ReplyDeleteI don't know if you have all ready done this, but one of the reasons I use sockets for all my ICs is so that, even after I have tried and failed to diagnose a problem build, I can salvage as many bits as possible and rebuild the board. Often times, there is an error that I just can't find - such as a tiny bridge or bad passive component - and it takes making a new board to correct it. It's not very scientific, but, as I said before, the layout works. I've built several of them.
DeleteIf something is not working right, I suggest having another go at it. Stripboard building takes an enormous amount of patience. And often times, some profanity. Good luck!
So I replaced the Smokey pot and sprayed the board with a contact cleaner and a toothbrush....try to guess....now works....even the led....The Mystery of the Stripboard episode 24...the saga continues
DeleteSi , funciona y lo estoy por encajar.
ReplyDelete