"Little Angel" - Super Simple PT2399 Mini Chorus

[slacker]

If you look at the latest datasheet it recommends not using less than 1k resistance off pin 6 at power on, the old ones never had this warning. http://www.princeton.com.tw/downloadprocess/downloadfile.asp?mydownload=PT2399_1.pdf

I think it depends on the individual chip as to whether it will work with less, I've got 2 Echo Bases both built with 3 year old PT2399s from Smallbear. The first one I built never has any problems no matter what the resistance is but the other one occasionally locks up if I turn it on with the delay time on minimum.

[frequencycentral]

^^^

Thanks Ian, I hadn't seen that particular datasheet with the below 1K warning. The difference between 100R and 1K in terms of delay time is about 8ms. So I guess we say the value for R1 needs to be 1K to avoid lock-ups. Can anyone comment on the audible difference between 100R and 1K?

[Earthscum]

Tonal difference is all I noticed, and it was slight. It definitely increases the perceived depth of the effect, IMO, but not bad. my Sewer Pipes is where I really noticed tonal change concerning the delay. Between about 220R and 1.2k there was more change, and after that the waves become too separated. I don't remember that much change in the LA...

The LFO section of my LA went kaput for some reason, or I'd just check it out for sure since I have the adjustable delay. If I get it working, I'll get back to ya.

[Pigyboy]

Thanks to you all for the new info. I will build another today and use the 1K and report back what happens.
cheers,
Chris

[Govmnt_Lacky]

Thanks to you all for the new info. I will build another today and use the 1K and report back what happens.
cheers,
Chris

Definitely interested in your findings! Please let us know! 

[BoxOfSnoo]

^^^

Thanks Ian, I hadn't seen that particular datasheet with the below 1K warning. The difference between 100R and 1K in terms of delay time is about 8ms. So I guess we say the value for R1 needs to be 1K to avoid lock-ups. Can anyone comment on the audible difference between 100R and 1K?

I tried it on my breadboard... you can kinda hear that it's doubling, though just barely.  My circuit seems to work with a 100R, but I also added a delay time pot as well for longer delays.

If your PT2399 won't work with 100R you can still get a decent sound out of it with 1K, but it will be different.

[tyronethebig]

Just finished this with the 1590 layout! Had a problem (small bridge between pin 5'n'6 of IC2) but it was an easy fix and now it sounds great! Thanks Rick for the killer pedal!! Hopefully someday I'll be able to contribute with a sweet design of my own. Pics as soon as the enclosure actually gets here 

[tyronethebig]

Le sigh, I walked away to eat lunch and when I come back it doesnt work?

Ne5523 - Very close to ricks readings

PT2399
1-5.01v
2-2.32-2.42
3-0
4-0
5-5.01
6-.58
7-0
8-4.58
9- 4.84
10-.35
11 thru rest 2.41

*frustrated*

[frequencycentral]

Sounds like the PT2399 has locked up. Switch it off and on again and it'll probably work. Also try a 1k resistor for R1 instead of 100R.

[tyronethebig]

It worked! Kinda

I turned it off and on and the effect came on, I then soldered in the 1k at R1 and its back to not working city. With a voltage readout similar to the one I described.

[tyronethebig]

I spoke too soon, it works now.
Right before it kicked in the modulation I very slightly turned down the voltage to the pedal. I read earlier in the thread that the "Onespot didn't play well" with this circuit. I wonder if thats my problem. Thanks for being quick on the draw rick, I'll play around with this until its stable.

[Pakaloabob]

Although it is an annoying problem I'm glad I am not the only one who has experienced the issue of the PT chip locking up. At least it is well documented in this thread so others will know to try other power sources. For me, the Danelectro power supply works well.

[tyronethebig]

BTW - this sounds really cool distorted with both speed and depth around 8 and ripping tritones. really agressive. kinda like...a little demon 

[jable1066]

Bahhhh I fixed the little bugger after having problems with it and it keeps like not working. I'll switch it off and on and it'll not work then after a while it will work. However, one thing I noticed which is definately the route of the problem (I think it'll be safe to assume it is anyway) is... my voltage regulator and PT2399 are getting MEGA hot. Anyone know why these could be getting hot? I don't have a 78L05 to hand... I only have a 7805 which is too huge to fit in my socket So I'll have to wait till tomorrow to go buy one from the electronics shop near my house. I've reflowed and cleaned up the board probably 4 or 5 times now, somehow without lifting traces but it probably can't go on for much longer...

[GodSaveMetal]

Must see the gut shots on this one! Absolutely beautiful!!

What are the level mix and delay pots??

[Earthscum]

Delay just gives me a range from the 100R to 10k. When I was breadboarding, I figured out that this circuit needs a little bit more delay for bass guitar. The mix pot is a 100k in series with the 10k wet side output resistor. When you increase the delay, it really starts to cut across the dry signal, and with bass, you don't want a full-out delay, or your guitarists start running all over you (gotta keep the punch and presence up so they actually sound like they might actually be playing in time   ).

Page 8 has the mods.

[GodSaveMetal]

In these mod: the pots market for DELAY, MIX and LEVEL are the correct positions?

[tuckster]

Did someone say Arch Angel ?   
The wait is agonizing...

Hi Rick, something new about the arch angel?

[GodSaveMetal]

I´ve made a layout for the mod of this pedal; it is correct?

[GodSaveMetal]

UUUUPSS!!! some mistake; here are the correct layout, you see an error? please post it! thanks: