UVICS - Univibe In a Crybaby Shell

[RedHouse]

We really need to focus on the hug thing, in fact probably now a group hug is in order ...c'mon RG, GP, shall we?

[GP]

Could be. Doesn't feel like a true troll, though. I think his agenda is pretty much spite, not trolling. It's subtlely different. In any case, the most effective response to PA attackers is to call them on it. Brad's said he's misunderstood and that he's trying to be good, please don't be weird at me any more, R.G.

OK. Can do.

Oh yes... i absolutely agree. My take on this is Brad has a problem with the green eyed monster. I can see how it must be tricky for you to just sit there and take it when it's, again, clear as day your intentions with this design are purely altruistic. Troll or spite, he's still trying to wind you up and it makes me sad to see it affect you. Battle ye not with monsters, R.G., and thankyou very much giving so much to all of us.

[RedHouse]

Oh yes... i absolutely agree. My take on this is Brad has a problem with the green eyed monster. I can see how it must be tricky for you to just sit there and take it when it's, again, clear as day your intentions with this design are purely altruistic. Troll or spite, he's still trying to wind you up and it makes me sad to see it affect you. Battle ye not with monsters, R.G., and thankyou very much giving so much to all of us.

You've got it all wrong GP, I'm just trying to help.

Peace-out.

[GP]

We really need to focus on the hug thing, in fact probably now a group hug is in order ...c'mon RG, GP, shall we?

You know, I'm all for hugging, Brad, but I think I'd be afraid, on the basis of your behaviour in this thread (and the last one), that you'd be stabbing me in the back at the same time.
Chill out! You're clearly an intelligent guy. R.G. is an intelligent guy. This is a place where intelligent people should come together to do intelligent things... not have petty fights or behave like a two year old.

[Jazznoise]

[RedHouse]

...Chill out!...

Clearly there is a lot of angst here, I'm trying to side step it though and move forward with this great project of RG's. Offering up some personal insight to save some folks some trouble.

C'mon lets move forward, be nice, solder stuff, play music.... on our UVICS's!

[Brymus]

Anyway...
I am thinking of trying the diode trick to the Vreg,or would it be better to use the LM317 that I have plenty of ?
Could I just tack the resistor to the IC's legs,what value resistor is close enough?
I am guessing over 15V is better here than less.

Also RG
I used (the only dual pot Radio Shack has) a dual stereo 100k audio log pot,each pot has 4 lugs,3 on top 1 on bottom.
The bottom lug is connected to the wiper too,maybe each pot is stereo,hence the 4 wiper lugs ?
Maybe the taper issue is in my wiring of this pot/s ?

If you could post the daughter board for using a single pot/with LDRs ,I may try that next too.
I will play with the LFO caps and see if the treadel operates more evenly across the range.
Its range of speed now is :
One flash every second min ,or two flashes a second max speed.

I was thinking that the speed indicator would circumvent the need for a 3PDT and LED.
But I realize now it would be on all the time even in bypass.
I am still going to add it though,my pedal board can be the light show at the same time.  

[R.G.]

I am thinking of trying the diode trick to the Vreg,or would it be better to use the LM317 that I have plenty of ?
Could I just tack the resistor to the IC's legs,what value resistor is close enough?
I am guessing over 15V is better here than less.

I'd go with the 317 if you have it. The pinout is different, of course. Um, resistor values.
The output of a 317 maintains a 1.25V nominal voltage across the top resistor, which they usually set to be 240 ohms in all the app notes. With 1.25V and 240 ohms, the current through the 240 is 5.2ma. You want a voltage of 15V on the output, and that makes 15-1.25V at the adjust pin, or 13.75V. The bottom resistor has to eat that 5.2ma because the adjust pin is designed to accept as close to no current as they could make it. So the bottom resistor has 13.75V across it and 5.3ma through it, or 13.75/0.0052 = 2644.23 ohms. Call it 2.7K.

I used (the only dual pot Radio Shack has) a dual stereo 100k audio log pot,each pot has 4 lugs,3 on top 1 on bottom.
The bottom lug is connected to the wiper too,maybe each pot is stereo,hence the 4 wiper lugs ?

Hm. Been a long times since I saw one, but they used to make four-terminal pots with a tap in the middle of the resistive element for Fletcher-Munson loudness compensation.  Wouldn't expect Radio Shack to have one, though. Is the fourth terminal ALWAYS connected to the wiper? If, so , it's just an alternate wiper pin.

Maybe the taper issue is in my wiring of this pot/s ?

Don't know. Why don't you check the taper by writing down the resistance to the CCW pin from wiper for 0, 1/4, 1/2, 3/4, full? That would tell us the real taper and let us make some guesses. I suspect it's the pot taper, not your wiring. We'll see.

If you could post the daughter board for using a single pot/with LDRs ,I may try that next too.

It'll go up on the next iteration of the PCB print. You can just print that section.

I will play with the LFO caps and see if the treadel operates more evenly across the range.
Its range of speed now is One flash every second min ,or two flashes a second max speed.

You ought to be getting more range.

I was thinking that the speed indicator would circumvent the need for a 3PDT and LED.
But I realize now it would be on all the time even in bypass.

Yep. It does that. I'll go mess with how to make one blink and be an indicator too. Maybe another baby board.

[Brymus]

Thanks RG
I am really diggin this pedal.
I'll get some more accurate info and report back.

[PRR]

> they used to make four-terminal pots with a tap in the middle of the resistive element for Fletcher-Munson loudness compensation.  Wouldn't expect Radio Shack to have one, though.

Standard RS item for decades. Is a $2 generic replacement Volume Pot for the millions of stereos sold 1970-1990. (Older rigs used 250K; recent gear is in-chip.)

Is inexpensive and generic quality; I used to buy several because about 1 in 10 had some glitch (skip in track, obvious channel mis-match).

Is "100K" (generally 75K-95K), "Audio" taper (really two linear segments with "5" giving about 15%). As volume-control, action is smooth 0-4, hardly changes 4-5, increases quite a bit 5-6.5, and rises smooth to 10.

Tracking as volume-potentiometer is usually better than 2db but rarely better than 1db through the middle.

The odd 4th terminal is a track tap near 40% rotation. A fair number of old hi-fis did, as you say, sport "Loudness compensation" (invoking Fletcher-Munson is gilding a mule). In general, you ignore it.

> check the taper ... CCW pin from wiper for 0, 1/4, 1/2, 3/4, full?

The 1/2 point is problematic on an Audio-taper pot because that's a "splice" in two linear tapers. Grab a Fender 0-10 knob and write all 11 values. You may find a sharp jump from "5" to "6". Also sometimes a sharp hop-on between "0" and "1".

Looking at the app and the RS part.... If the end-points are right but the lows cover too much travel, try 22K from each "loud tap" to bottom (common).

[R.G.]

Thanks Paul. I clearly have become a little distant from Radio Shack's parts stocking.  I had no idea they'd still stock that.

[R.G.]

Someone asked in a different thread, and as I had my drawing already done for the UVICS work, I posted a drawing of the hole locations for the one example of a Crybaby shell I happened to have handy. It's the one I measured to lay out UVICS; as such, it's subject to the little variations from shell to shell and manufacture date of the - what, 45 years now? - history of the Crybaby.

As noted in other places, the Crybaby trademark is used for reference only and remains the property of it's current owner, whomever that is.


ARGH. I actually have to type in the link if I want it to appear, don't I? It's on the first page: http://www.geofex.com

[Brymus]

Hey thanks for that Paul !!

So if I understand right, its add a 22K from the extra tap (on the bottom pof each pot) to lug 1 of the top three lugs ? (on both sides of course)
Did I get that right?

The treadel/speed control actually operates backwards right now,so I was going to switch the wiring of lugs 1 and 3
Right now I have lugs 1 and 2 tied together on both pots then thats (lugs 2 and 2) tied together to one lead (pad W2 on the layout).
Lug 3 of each pot is the other two leads.(pads w3 and w4)

Before I proceed I thought some voltage readings would be helpful:
In 18.42 VDC after the 100R 14.6/.8 VDC

Done with a 1K sine input and the LFO at max speed. (by the treadel)

Q          E                      B                     C
1)     .756                1.134                1.538/.542
2)    1.240               1.542/.547        3.212
3)    2.612               3.212                9.23
4)    3.370               3.780                11.97
5)    2.772               3.370                9.21
6)    3.396               3.792                11.97
7)    2.823               3.397                9.16
8     3.386                3.791               11.97
9)    2.789               3.386                9.17
10)  4.30                 4.80                  11.97
11) 4/12DC              3/10DC             14.4/14.6
      1.5/3.5AC          1.3/2.9AC
12) 3/11DC             3/12DC              14.3/14.5
      1.2/3.2AC          1.2/3.4AC   
13) 3/8 DC               4/9 DC              9/12 DC
                              .9/2.2 AC           .5/1.5 AC

Where I could I took AC/DC readings but the fluctuations made these just my best guesses after watching a little while.

[Brymus]

I didnt get a chance to measure the dual pot yet but I shot a vid that shows the min and max bulb flashes.
I will post it soon.
I did count teeth on the gear and the majority of speed change happens in 3 teeth of the gear ,no foolin.

[R.G.]

Three teeth? Wow.

That sure has the smell of a log (or reverse log) pot set up the wrong way.

[Brymus]

Here I mapped it ,in circuit
At max treadel heel, or pot max CW
tooth        pot 1        pot 2
1               1.8r          1.6r
2              238r          1.3k
3              17.3k         15.27k
4              33k            33.83k
5              55k            50k
6              61.5k         61k
7              62.9k         63k
8              64.6k         64.4k  
9              66.4k         66.5k  
10            67.3k         67.3k
11            68.4k         69.4k
12            69.3k         70.4k
13            69.3k         70.6k  
max toe position or CCW on pot  

Now out of circuit each pot measured close to 100k ,one side was 97k, the other 106k  .
Suggestions ?      

[Brymus]

OK the way it is now lugs 1 and 2 are tied together.
If I take the 4th lug and tie it to lug 3.
Then the pot starts at 14k goes down to 1r then back to 14k   

I really dont understand this pot.

[Brymus]

OK then
* I reversed how I wired the pot.
* I lowered the LFO caps to 4.7uf
* I lowered R43 and R 42 to 2.2K

WAY WAY better !!!  


Now the taper is very usable and works - toe fast, heel slow.
Now my speed goes from probably 4 or 5 a second down to 1 every two seconds.

Edit: probably more like 3 or 4 a second max and 1 every 1/1.5 seconds min.
I am gonna try lowering R42- R43 even more,as the max speed I like causes the FS to cycle.
But yeah now its fun using the speed control.

[Brymus]

R42 and R43 are now 1.2K and I am thinking of lowering them more or halving the LFO caps again.
I like the really fast speed then slowing it down,...what can I say ? 

I did the diode trick to the Vreg now it puts out 14.25 volts.

I socketed the input resistor R1 and after 47K most of the distortion on low notes was gone.
But trying to rid the blatty distortion with full bar chords using my neck pup and its at 150K now.
And if I give it a full strength strum it will still distort a little bit.

Sure am glad all the wires enter on the side ,I have pulled the PCB and de-soldered/re-soldered alot of times now.
Still no wire breakage, but lost 2 pads so far,from over heating them.

I was thinking about doing the indicator mod with an LED in series with R 46 to ground,then using the 3PDT to short out the LED in bypass mode.
Do you think that will work OK ?

I am also thinking about pulling TR1 and making it a pot on the outside,
as I like the tonal variety you can get by dimming /brightening the bulb.


Is there anything else I can check /try for anyone ?
After its done I am going to gunk the wires,and see how the transistor swaps work out.

[RedHouse]

Good work Brymus!, post a pic when you get a chance.