9V Electric Mistress Pin Voltages (From Markus' Layout)

[sta63bmx]

OK, here is an image file with all the pin voltages I recorded on my 9V Electric Mistress build so far.



I do NOT have this boxed yet.  It's laying out on my bench with a bunch of wires splayed everywhere.   I've got a couple comments/questions, though.

Comments

1. I noticed that after I was done ironing, the pads were touching in some places that they shouldn't have been.  I scraped the transfer off before I etched it and then it was ok.  Smaller pad sizes might have helped with that?  I dunno.  The fine details came out in the iron and etch, though.  I mean, the REALLY fine lines came out clean.  Pretty cool!  The ironing surface wasn't perfectly flat, so maybe I just got too much pressure in some areas.

2. Did it say in the project file which lugs were 1, 2 and 3? lol  I must have missed it.  I had all my pots wired backwards the first time.   What's the convention when looking at the BACK of the pot?  Is there a convention?

3. Tons of room for everyone on the board.  No wacky squeezing or bending or anything.

Questions

1. What *exactly* is the clock trim setting?  I read through that old copy of Device from Mark Hammer's page and looked through some search results and I am just not quite getting it.  I apologize for my dumbness.

2. What the heck is up with that 2k7 resistor on the battery input pad? lol  Is the battery supposed to be charging from the power supply when the unit is plugged in or...?

Sounds/Trimpots

1. The bias trim I found to be THE most critical.  If it's out one way or the other, I got zero flanging.  There was an area where I didn't hear any distortion, but it would clip at either end of that range.  I couldn't hear any level change inside that sweet spot, and it was pretty wide.  I didn't notice much change in the flanging sound.

2. The feedback trim controlled the depth of flanging and gave weird spaceship sounds when the unit was in oscillation.  When the unit was close to oscillation, I noticed more white noise kind of sound.  Is that from the clocking signal?

3. The clock trim was the most confusing to me.  In the middle of the range was where I got the worst noise.  I was running into a semi-cranked tube amp, there are long unshielded wires, I was expecting a little noise.  No big deal.  I am just not fully understanding what that knob does.  I fooled around with the three pots for a while, adjusting the clock trim trimpot and I found my favorite sounds towards one end or the other.  In the middle, the sounds I got were more "detuned" and less useful, with more wobble and weirdness.  I was looking for that slower, more musical sound, and was better able to get that at one end of the trimpot's travel.  Less clock noise, too.

4. The unit was very quiet where I had it set.  Aftermy Pulsar Experience that was a pleasant surprise.

Overall Impressions

1. The non-true-bypass dry signal was VERY similar in gain to the flanged signal.  They were close enough that I'd rather do non-true bypass switching.  The tone sounded fine to me.

2. I really liked the slow, subtle sweep.  The intro to "Mayonaise" by Smashing Pumpkins is in there, but so is "Love Stinks" by...jeez, Nazareth?  But the slower sounds I liked best.  It doesn't completely overpower the regular sound and you can still PLAY with it, not just make weird noises.

3. The vibrato was also handy.

Summary

It worked on the first try, so props to Markus for the layout and Fransisco and Steven (?) for the schematics.  I'm sorry if I left anybody out.  Now it's time to make a cool box.  Where could I wire in an LED that would flash in time with the LFO?  I plan to make a super-pimp status light scheme for this box.  It's for my coousin's birthday and he has no idea.  I'm super excited about giving him this present.  I don't think I've ever been so excited about something I got for somebody.  I'm honestly surprised I got it to work right away.  Thanks for the layout and schematics, guys.  This is the coolest present ever.  Kinda.  Oh, here's the board.

[sta63bmx]

Those readings were all made with a multimeter looking at DC voltage, by the way.  I'm sorry I forgot to mention that.

Pin 7 of the LM324 provides a 50% duty cycle square wave at the same frequency as the LFO, so I think I can use that to switch the "flashing light" indicator that I want.  Pin 7 is the output of one of the four opamps on that IC.  This is where my glaring lack of electrical knowledge comes in.  Those two sections of it with the 1M cap are the LFO, right?  And is it just a square wave LFO with one opamp being driven back and forth to its rails?

I am ASS-SUMING that the output where I see that square wave can supply enough current to drive the base of a transistor without messing up the rest of the regular EM circuit.  Is that true?  I was going to connect an LED inline with the collector of some little NPN (got some 3904's handy) and then ground that emitter to the same ground as the on/off LED (so it would be switched by the footswitch) and THEN drive the base of that NPN with the output of pin 7 from the LM324.  Do I need a base resistor or something?  If someone could let me know what rules of thumb to follow here, I would appreciate it.  The voltages already seem perfect for driving that gate on and off.

The LFO can go so slowly that I think a permanent "status" light is necessary, but the flashing light would be nice, too.

[analog kid]

thanks so much for doing these and as well for even posting them here for all so that they WILL be here from here on. Since I know that you basically went through the trouble as favor to me thought I'd make it known it's greatly appreciated , you put some effort into it not just scribbling reading down! I'm sure others will appreciate this file in thefuture
  If this doesn't help me track my error/problem I don't know what will! and i'll update with my progress
the kid 

[sta63bmx]

Dude, I owe everybody on the site so much for the free layouts and help that I could never pay it back.  I can't wait until yours is up!

[A.S.P.]

Thank You, David %^&*erell and Howard Davis
for having provided Mike Matthews with such fine pedals!
(like you did, and partly still do...)

[sta63bmx]

I am striking out on getting a flashing light that I like.  Pin 7 on the 324 is a 50% duty cycle square wave, which is perfect, but I CANNOT for the life of me get it to drive a transistor at 50% duty cycle.  It goes from about 0.6V to about 5.4V and the frequency is controlled by the rate pot.  Here's what I tried first.

1. Put a current limiting resistor and LED between V+ and the collector of a 3904
2. Hooked pin 7 of the 324 directly to the base of the 3904
3. Connected the emitter to ground

At best I got a very faint light flash, using a pullup or a pulldown.  By fooling with the current limiting resistor I could get a brighter flash.  But it was like a 1-10% duty cycle, tops, like a very brief flash.  It was lame.  So I looked at the signal on pin 7 of the 324 and tried to see what impedance it was.

I put a decade resistor between pin 7 of the 324 and ground, and I had to drop the resistance to less than 10k to see any change in the waveform.  That signal should have plenty of oomph to drive the base of a transistor.  So why won't it work?  I'm trying to rig a transistor like the blinking light mod outlined here in the runoffgroove EA trem schematic: http://www.runoffgroove.com/eatremolo.html

What act of gross stupidity am I committing?  I thought if the base was at least ~ 2V more positive than the emitter than the transistor would turn "on" and switch on the LED.  If I monitor pin 7 on the scope while I connect it to the base of the transistor, I'm not seeing any change in the waveform.  So it isn't like the transistor base is pulling that down to nothing.  There must be something I'm doing wrong.  Probably something dumb, knowing me...

[analog kid]

 I guess I'll ask for some opinion from the forum here as well and the wealth of knowledge here.
   I have had problems getting mine to flange , originally getting only clean signal abslolutely no affect from any controls at all.     but now I'm not getting any signal , so not sure what happened there.
Based on  voltages though,  All is well based on the voltages here, EXCEPT for the two ICs' SAD1024 and flip flop 4013.  Of which the biggest mystery IS...
  What possible causes could allow Pins 3 and 14 of the SAD 1024 and 2 and 5 of 4013 (which are only connected to one another) be reading at ZERO volts if not due to being shorted to ground anywhere?
My entire problem so far as I can tell seems to be coming from this area.
  And I'll note , since the SAD 's are so rare , that I borrowed mine from a Ross Flanger I have and it does flange in that circuit as well as Pins 3 and 14 giving voltage of apprx 1/2v+ . So hope that tells me it's not the chip.
Any ideas??

[sta63bmx]

Quick note, I tried using a 74128 NOR gate to drive the transistor base.  Using the LM324 pin 7 as the A and B input to the NOR gate and the Y output to drive the base, I could make it work.  The trouble is that I think the chip draws WAY too much current.  I used a voltage divider (drawing off some power from the board like I would have done in the pedal) and I kept getting a HUGE voltage drop to the middle of the divider.  I had to use a voltage divider to get 5V for Vcc on the chip, and I noticed that the voltage was *way* low.  I think the chip is drawing something like 10-50 mA, probably more current than the whole board, maybe?  It was nuts.  I had a 133 ohm/5k divider, and right after that 133 ohm resistor, the voltage was down to about 5V from 7.2V.

I think I'm going to give up on the flashing light unless someone has a great idea.  I'm just pissed because there is a perfect control signal RIGHT THERE and I can't seem to make use of it.  Here's a picture of the signal on pin 7 of the LM324.

http://i55.photobucket.com/albums/g154/sta63bmx/effects/9v_electric_mistress/LM324_pin_7_small.jpg

I am just not sure how to implement that to drive a transistor.  I thought I did, but evidently I don't!

[sta63bmx]

I am the dumbest dumbass to ever be dumb.  I think I am the king of "I can't get it to work!" and then ten minutes later "Fark, I'm dumb."

I was trying LAST night to hook that signal directly to the base of the transistor.  Bear with me.  This is for an NPN transistor.

1. The base-emitter junction just kind of looks like a diode.  So the base will be about 0.7V above the emitter.  And if you send a tiny amount of current into the base (does it actually go to the emitter? and doesn't Vbe have to be bigger than some threshold?) you can make a HUGE current go from the collector to the emitter.

2. By hooking the signal DIRECTLY to the base, I was forcing that pin to be no more than 0.7V above the emitter, which was tied directly to ground.  So goodbye LFO signal.  And then it would never have enough voltage from base to emitter to turn the thing ON, so no flashing light.

So today I hooked the transistor up EXACTLY like last night only I put a 360k resistor in series with the base.  So now I can still get a tiny current but all the voltage drop occurs across that resistor.  And so the LM324 pin keeps doing what it's doing, but now the light is flashing.

I fell asleep reading AofE last night, but I'm going back to the transistor chapter to try and figure out where I'm not quite GETTING it.  I have always thought of "turning on" an NPN transistor by applying a positive voltage to the base relative to the emitter.  The single diode drop from base to emitter would have killed the voltage, so no triggering.  That makes sense.  But is is the base current turning the thing on or is it the voltage relative to the emitter that turns it on?

I'm going to put the flashing light stuff and regular indicator light stuff on a little piece of perf.  I am going to filter the PS for the flashing light some to try and make sure I don't pick up a pop.

[sta63bmx]

Does that 200 ohm resistor between PSGND and V- float the ground plane relative to the negative battery terminal?  This is how my voltages all measured.

Negative Battery Terminal: -1.8V
PS GND: 0V
PS +: 7.2V

Is that done to try and cut down on noise like how you float an AC filament supply on a DC bias?  I'm not understanding the why of that particular resistor.

[analog kid]

 ..... no ideas, anyone, on my voltage probs around the SAD and flip flop??  anyone experienced with these 1024stage  BBD's particularly and what reasons besides short to ground could cause no vltge reading on pins 3 and 14.

[wcampagner]

Hello,

I'm trying to make the same circuit (electric mistress 9V - Markus W.).
But i have just clean tone when testing.

I've made some measures to compare with the ones here.

I saw a strange thing:

Negative Battery Terminal: - 4,6V
PS GND: 0V
PS +: 4,4V

I was suspecting some short on the board, but i've already verified everything.
I tested on two diferent boards with the same results.

What i notice is that when i take out the LM324, i get the correct values.
But i don't thing the CI is burned because i tried with diferent ones (maybe all of them are burned?).

When i take out the RC4558 i get almost the correct values too.

I've made some substitutions:

Resistors
200 R -> 220 R
510 R -> 560 R
6k2 -> 6k8
13k -> 12k
24k -> 22k
30k -> 33k
62k -> 68k
200k -> 220k
1M2 -> 1M5

Cap
1n -> 1n5

Diode
1N961B -> 1N4742A

I couldn't find the correct values, so i put what was the nearest.
I don't think this is the problem.

So if anybody could help me, i'd be glad.

Thanks a lot in advance,
Wagner.

[markusw]

In the original Mistress the 2k7 at battery V+ is bypassed if no ps is connected.
So easiest way is to connect both, battery and ps V+ to the PS+ pad.
Hope this helps.

[wcampagner]

hello Markus,
Thanks for the answer.
i'm not using battery... so i'm only connecting the PS...
The problem is with the 200 ohm resistor conectec to gound...

So my reading are:
ps - terminal = -4.6V
ps + terminal = 4.4 V
gnd = 0V

for some reason i think the circuit is eating a lot of current...
that's why the ps - is -4.6V... it should be around -1.8V...
i was thinking that is was a short or something like that...
but i have the same problem with 2 boards...

does anybody have any advice?

thanks,
Wagner.

[markusw]

BTW, I replaced the 200R with a jumper.

Regards,

Markus

[wcampagner]

Hello Markus.
Thanks for the answer.
I tried to replace with a jumper too.
This way i get higher voltage from the table, but proportional values.
But i get only clean tone not flanger.
Any more ideas i could check?
Thanks again,
Wagner.

[markusw]

Do you have a possibility to check if the LFO and the VCO are working?

Regards,

Markus

[wcampagner]

Hello Markus W.,



Thanks for replying.

Can you tell me how to do it?

I think i need to understand a little bit each part of the circuit because i don't know all parts yet.



Because i can get clean tone i can assume that the TL072 (input buffer) is working properly?



I know that the LM324 is working too because i can see that the values are changing according to the value tables above.

But in diferent values... and also i could check the square wave on pin 7 of this IC.

I have only a DMM... i don't have an osciloscope... but i can get one if it is needed.



What else could i check?



Thanks,

Wagner.

[wcampagner]

Hello,



I'm back again trying to make the electric mistress work.

I have now almost everything working great.



The effect is working very good.



Now the problem is with noise.

I'm getting what i think is a clock noise (noise in the same frequency as the oscilator).



I've used the biggest filtering caps as suggested on the PDF project file.

I also changed the CLOCK TRIM to get the lowest clock noise.



But I'm still getting CLOCK noise.



There is one point when the FEEDBACK and the RATE controls are on max (fully CW) and then when i change the RANGE control there is one point when the CLOCK noise goes away. That's teh way i think it should be for all setting.



Is there anything else i could do?



Thanks in advance,

Wagner.

[markusw]

Hey,

glad you got it working 
Sorry I didn't get back to you. 
I left for holidays on July 11th and when I came back I simply forgot to check this thread...

Where was the bug finally?

Regarding your noise issue: does the frequency of the noise change at the rate of the LFO?

Do you happen to use a switchmode power supply, btw?

Peace,

Markus