LFO for DELAYS (echo base lfo not working on +/-12v

[loss1234]

hey there

building an echo base for a rack device. everything works great on +/-12volts except the LFO section. anyone know if i should disregard the +5volts  on pins 6 and 3 of UA1/B? is this lfo super sensitive to specific voltages?


is there another easy OPAMP lfo i could stick in that will work on +/- 12volts?

i DID get the current sink input to work with an external LFO (tapping in at mod depth pot) so I KNOW the rest of the circuit works REALLY WELL. my god, this thing can do so many crazy sounds.

thanks

[frequencycentral]

Use the one from the Roland M-172 module I posted on your other thread.

[loss1234]

i cant read that schematic...i tried hard but i cant


thanks

[frequencycentral]

My redraw of the Roland LFO. the 0.01u cap can be adjusted to alter the speed range. The stock LFO just has triangle out, I found that the output of the first opamp gives a square too. the square is much higher output than the triangle though, you may want to attenuate it if you use it.

I have one of these running on +/-15 volts in my modular, another running on +/-6 volts using a 12 volt power supply and floating earth in a small SFX synth I built.

Do you still want me to redarw the Gate Delay?

[slacker]

If you're running it on +-12volts then pins 3 and 6 of the LFO and pins 3 and 5  of the other opamp should be connected to ground.

The LFO is just a standard 2 opamp triangle LFO running on a single supply. Normally you'd use a voltage divider to give you a 1/2 supply virtual ground, like you see in almost all stompboxes with opamps in, and connect the relevant pins to that. With the echo base I figured that as there was already a solid 5volt supply for the PT2399 I would save a few components and use that to bias the opamps as well. That's why the LFO doesn't like it if you run the echo base on a weak battery because the bias moves too far away from the centre of the supply.

By the way make sure you only run the CD4066 off +12 volts and ground not off +-12 volts, because its maximum working voltage is only 15 volts.

[loss1234]

hey everyone

frequency-thanks a lot! i would love the 555 gate delay but i felt bad about asking you to redraw it.

slacker-wow, you made the echobase eh? i CANT tell you how much i love it!

since i couldnt get the lfo working today, i had just plugged a JACK into the mod depth pot and WOW, ANY cv source i chose from my Modular synth opened up a whole new world of screwed up tones.

this has got to be the most powerful FX i have made in a long time, possibly ever. i am already in the process of ordering a bunch more pt2399 chips.

thanks

[slacker]

slacker-wow, you made the echobase eh? i CANT tell you how much i love it!

this has got to be the most powerful FX i have made in a long time, possibly ever. i am already in the process of ordering a bunch more pt2399 chips.

Thanks, have you tried a sample and hold CV voltage that's really good fun

[loss1234]

yes i tried it

but i must say, my WOGGLEBUG was the best thing. if you havent built one i highly recommend (a grant richter design)

all in all, every module i plugged in sounded great. so i assume this is really just a CV in -is it linear? (i assume so as there is no expo converter)...is this what you might call a current sink?

anyway, thanks so much for such great work.

so simple to build to compared to BBD designs.

[frequencycentral]

frequency-thanks a lot! i would love the 555 gate delay but i felt bad about asking you to redraw it.

It's no problem my friend, I'll get down to it over the next day or so - I have a week off.

Also, I'm interested in a fellow modular user - what do you have? I have a 5 module Roland 100m with a further 8 DIY modules including Moog and Oberheim filters. 4 VCO, 4 VCF, 3 VCA, 4 ENV, clock dividers, sequencers, signal gates etc.

[slacker]

but i must say, my WOGGLEBUG was the best thing. if you havent built one i highly recommend (a grant richter design)

I've looked at that a few times seem really interesting, I'll add it to the to do list.

so i assume this is really just a CV in -is it linear? (i assume so as there is no expo converter)...is this what you might call a current sink?

Yes the base of the PNP transistor is basically a CV in, depending on what you're going to drive it with it might be worth adding a buffer in front of the "depth" pot, but most synth CV sources will probably be fine. The response is fairly linear, but to be honest I just  experimented with component values until it sounded good.
I think it's acting as a VCR (Voltage Controlled Resistor) rather than a current sink but I'm not too sure about the technicalities.

[loss1234]

slacker-very cool. i might try this circuit in other applications that need a VCR. very simple but works great.

my modular, well my modular is 100% DIY. i actually just started DIY last JULY (When i quit smoking) and i dived in head first. my first module was a kit (the PAIA midi 2 cv) but everything after that has been either veroboard or blank PCBS bought from ray wilson, ken stone, ian fritz,etc. (I SpEND LOTS OF TIME ON ELECTRO-MUSIC.com they have a great synth diy community)

anyway, i have about 14 modules now, some self designed, the rest are either standard fare (2 vcos, (ken stone and ray wilson) a ssm 2044 filter (foniktronik pcb)
an adsr, a multiple, a mixer, a wogglebug, 2 chaotic pattern vclfo's (ian fritz), a 4070 xor module, a cmos octave down (4040/4020) module, a diy serge negative/psotive slew (similar to the dual universal slope gen) a utility LFO (ken stone pcb) a ray wilson (self etched) sample and hold, a ken stone (pcb) vca, and a multi noise/random gates triggers module i etched myself.

there might be more..and THERE ARE a ton of pcbs i am still etching or populating. but for now i am working on a monster guitar effects box so the modular is happy as it is for a while. hell i spent a year building it and learning HOW to build it. build all my own panels and racks too. but it is NOT very pretty

sounds awesome though