Echo Base - a new PT2399 delay

[returntable]

yep, I can confirm now that there's no problems when using a DC Supply...

I'm just glad that all Problems are now solved

[i2k]

I just found this project & this is exactly what I'm looking for. Thanks for sharing this.

BTW, can we use 2 switchable pot for "time" control ? This way we can have a switchable "preset" of short and long delay, like Blackbox Quicksilver delay ? Is it simply just by adding second pot & a SPDT switch ?
If that can be done, can we do the same to the "speed" control ? If it's a yes, I imagine that we can build a switchable chorus & delay in a box, that would be a great fun...

[alteredsounds]

Could I use a spare sad 1024 in this or is this a mad question?

[Chawk]

Can a BC550 replace the BC560 that is called for in this circuit? 

[slacker]

No a BC550 is an NPN transistor, you need a PNP transistor. 2N5087s have been reported to work, but any high gain PNP should work fine.

[Chawk]

No a BC550 is an NPN transistor, you need a PNP transistor. 2N5087s have been reported to work, but any high gain PNP should work fine.

Excellent... thanks for the killer clips, by the way. This box sounds like it'll be fantastic.

One thing I've always hated about the delay I've been using is the fact that the echos cut off when the effect is bypassed. Thumbs up for that fix!

[Branimir]

I'm no wiz in digital electronics, but let's try together:

And now the tap tempo hehe...

I looked at the PT2399 datasheet and it seems like only resistance to ground connected to the pin 6 has effect on the clock frequency, hm...

The only thing that pops into mind here is the... LED-LDR combo... The tap tempo could control the oscillator circuit and the oscillator circuit could control some other chip that will eventually control the led voltage, of course this could be hard to calibrate, but I think it's possible... And of course by controlling the led voltage, we control the brightness of it (the led),  eventually the dark/light resistance of the LDR is the key part as it should fall into 1k to 50k territory, but that could be obtained by putting some resistors in parallel maybe to get the total LDR/resistor combo into 50k territory... Dunno, if anyone has any other idea, please share!

Help me out here, where should I start?

[SISKO]

Im working on it but with a diferent idea.
When finished ill post it

[Michael Allen]

With the LED/LDR model, it will take a ton of calibration to get the tap to match up with the delay time

but it sounds doable....

[Auke Haarsma]

My common sense says: what's the use of taptempo when you only have ~300 ms of delay available? To me it seems like too much trouble for too small an advantage.
My DIY-heart says: Go for it! I'm really curious if you can come up with a working design. I have a slow project going on with another new delay (based on pt2395 instead of 2399) which has 800ms of delay... I need taptempo there too!

[Branimir]

Yes, you're right for the delay time, guess I mistaked the 2399 for 2395, now the later one could use a tap function.

Generally, when doing delays on vocals in a live situation, dub-reagge or anything else, I usually find tap function useful between 200ms and 600ms, and it usually depends on the tempo of the song, never needed any longer delay time from 750ms for vocals, so I can see it could be useful with a guitar.

[slacker]

This actually has ~720ms of delay not 300ms but I'd agree with you, I don't think tap tempo is that useful. A much easier and IMHO more creative solution is to add an expression pedal to control the delay time, that's what I've done.

If you wanted to add tap tempo you wouldn't need to add an LED/LDR combo you could mod the part of the circuit around the PNP transistor because the delay time is proportional to the voltage applied to the base of this transistor. At the minute this is just driven by the LFO to get the modulation effects, but in theory a tap tempo circuit that produced different voltages for different times could be hooked up to it. This would work fine in theory but I don't know how easy it would be to acurately match the voltages to specific delay times. I guess it depends how predictable the response of the transistor/PT2399 combo is.

I'd imagine the hardest bit would be designing the actual tap tempo circuit, you're on your own there I'm afraid.

[spectraljulian]

Yay for Star Wars references. 

[DimebuGG]

I've just built mine with no problems..and I must say that this is way better than the rebote 2.5. Just one comment, I think the 100K FEEDBACK pot is too large!!!Maybe 25K-50K would be fine because this acts like the REPEAT pot in Rebote 2.5 which is 25K. Beyond 9 o'clock will start to create oscilations!!!DELAY tails is cool!..non-true bypass is not an issue plus switching is very much silent.

I used 6458DS opamp for the LFO and worked fine since(I just saw it in an old radio PCB and give it a try). I'll try TL072 soon.
And also 2N3906 instead of BC560, 2N3904 for 2N5088, 78L05(TO-92) instead of 7805. PCB measures 60mm x 70mm.

[slacker]

Cool, glad the part subs worked out, good to know it doesn't need specific parts.
If you want to make the repeats pot more controllable then replace R17 (20k) with a larger resistor, 100k is a good starting point.

[DimebuGG]

Cool, glad the part subs worked out, good to know it doesn't need specific parts.
If you want to make the repeats pot more controllable then replace R17 (20k) with a larger resistor, 100k is a good starting point.

thanks slacker.. btw, would it be the same if i'll change the pot(FEEDBACK) to a lower value i.e. 25K?

[bent]

OK THAT'S IT....YOU GOT ME.... I'M BUILDING IT....

IS THIS SCHEMATIC IS STILL THE LASTEST AND UPDATED ... 
http://www.eskimo.plus.com/fxstuff/echobase.png

THANK'S

BENT

[slacker]

thanks slacker.. btw, would it be the same if i'll change the pot(FEEDBACK) to a lower value i.e. 25K?

I don't think changing the pot to a smaller value will make much difference, it's the resistor that controls the gain of the feedback.

IS THIS SCHEMATIC IS STILL THE LASTEST AND UPDATED ... 
http://www.eskimo.plus.com/fxstuff/echobase.png

The latest one is here http://www.aronnelson.com/gallery/v/slackers-stuff/album170/echobase.png.html?g2_imageViewsIndex=1

[DimebuGG]

Ok..i've just read the other thread regarding the feedback resistor..anyways that 1uF in the LFO ive been using was an electrolytic("-" side to the out of the opamp and "+" side to the "-" of the opamp)..i'll replace it sooner with tantalum and see how it goes..

But this sounds ok to me with this electro..IMO...

[bent]

The latest one is here http://www.aronnelson.com/gallery/v/slackers-stuff/album170/echobase.png.html?g2_imageViewsIndex=1

thank's slacker....

i think i find a error in the schematic ...
At U1B, i think you invert PIN 4 and PIN 8 ,  you put LFO+ on pin 4 and on the layout http://blogs.yahoo.co.jp/anonymousfacelesscoward/19192939.html you put it on the pin 8
and vice-versa with pin 8.....

Bent