delay tempo tap

[muizac]

Hi Guys.

My very long email didnt get too much response, so i thought i'd  break it down a little.

Does anyone have any suggestions on building a tempo tap feature to set  the delay time on a delay pedal like the the AD-80 (or better). I'm looking for something similar to carl martin's delayla XL where you just tap in the tempo on the foot switch and the delay time adjusts automatically, but i'd also like to add a numeric display showing the actual tempo im setting. (so i guess in essence this display also acts as a bpm calculator, such as the one found in cubase sx).

any help is much appriciated. thanks

muizac

[smoguzbenjamin]

You'd need to do it digitally, since analog circuitry would be immense.... No I think you need to find someone who knows how to program PIC chips and do it like that. Then you could use a special digital potentiometer or a FET/transistor instead of a pot. Digital is good for some things ya know

[muizac]

hi.
yeah it sounds like digital is the way to go. This got me thinking, does anyone have a schematic for the Boss dd5 ? this uses a tap tempo feature that is controlled my an external pedal (but maybe this is an expression pedal, rather than a 'beat / tempo detector thats you'd get from an on/off switch) - anyway i thought it might be worth looking at it.

For those that are interested the delayla xl pedal with tempo mod is here http://www.carlmartin.com . i think the switch is a just a standard dpdt switch and not a photocell / pressure sensitive switch, although i have seen both of these used on DJ mixers, synths, and studio delays before.

I think 'cederic' has built one of these tap tempo units before, but im unsure what type of switch he used.

[smoguzbenjamin]

The DD-5 uses a simple spst switch for its tap-tempo function, but I'm not sure if it's normally open or closed. You'd have to figure that one out....

[Dutchie]

DIGITAL.......yeps that's my field of work....

The PIC sugestion is a good one, very easy to program, only few parts.
Maxim has nice electronic resistor IC's. most need a serial data stream as an input...can be done

Dont know bout Fet's as a use for this, takes some fidding to get a fet to act in a certain desired range......dont say it cant be done but i see fets more as switches max R or Min R.....But i can be wrong....i gotta stick to them 0's and 1's....i understand them hehe

[muizac]

an spst switch for my tap-tempo would be ideal.  i'd love to know a bit more about the circuit involved for a tap tempo feature - whether its the PIC approach or an alternative - can anyone elaborate? Or, if there's a DD5 schematic available that would also be great. (I've searched around and not had much luck).

Cheers

muizac

[The Tone God]

an spst switch for my tap-tempo would be ideal.  i'd love to know a bit more about the circuit involved for a tap tempo feature - whether its the PIC approach or an alternative - can anyone elaborate? Or, if there's a DD5 schematic available that would also be great. (I've searched around and not had much luck).

Don't worry about the switch type or even the circuit as the process needed to do what your asking is the main concern. I agree with others that a microprocessor based solution, be it PIC or otherwise, is the best way to do this but there is alot involved. Having a schematic of the DD5 would mean little. The tap tempo is done in the same manner as mentioned here.

This is mostly a software function and as such would require you to learn to program your own processor. Just realize that you need alot of skills to do it and if your not already comfortable with alot of the things involved then you maybe asking for too much. This is not a beginners project but don't let me stop you from trying.

The really abraviated lversion of the software logic flow would be something like:

1. Wait for switch tap
2. If switch tap wait for a few more taps while counting the time between taps
3. After enough taps average the time between taps
4. output new value to delay control

Its more complicated then that when you look at the things needed for each step like interupts, clocks, memory, arithmatic operations, algorithms, A/D and D/A, etc.

This topic has come up before so do a search.

Andrew

[muizac]

Sure thing, i appriciate it is probably not a simple project - but there has to be someone out there who has either built one before, or who has a diagram available. I have a bit of experience building analogue circuits, but none using digital componenets - at least if i can look at a diagram etc I can see whats involved for mysef, and ask around family and neightbour for any help.

[The Tone God]

There have been people who have done it, like the enginners for the DD5 , but its not just the work but equpiment too. You need the software to write the code, the code, debugging, a programmer, the microprocessor, some method of interfacing the processor to the delay timing control, etc. It would be tough to hack it in too especially with all the different delays out there.

I remember some other conversations have been had on this forum on this topic so give the search a try. They should give you more detail then I'm willing to get into right now about what is needed in terms of logic flow. I don't think there are any "ready to go" solutions out there so your pretty much stuck doing it yourself.

Andrew

[niftydog]

PIC or possibly PICAXE could do this.

first tap starts a counter1.

second tap stops counter1, stores value1, starts counter2.

third tap stops counter2, stores value2, averages value 1 with value2 and stores, starts counter3.

etc etc.

Use cumulative average value to set delay time, possibly via a DAC type affair for analogue delay, or modified bytes for digital delay.

[Darren N]

Assuming they are capable of the timing needed the pic (or whatever can handle the timing) could replace the clock for a BBD directly. Maths should be easy once you have the tap time. I just don't know how well pics do timing.

[Paul Perry (Frostwave)]

. I just don't know how well pics do timing.

Seeing as they are usually crystal controlled, I think it is up to the person writing the code :wink:
Certainly 'good enuff 4 rock&roll' !

[ExpAnonColin]

I believe the DD-5 is EPROM controlled and therefor sort of "too much" digital... most tap tempo delays, I believe, are... I think the echotap is PIC based, though I'm not sure.  I considered a long while back slowly laerning PIC so I could make a tap tempo analog delay, but it's just not worth it... a knob will do for me, you can just tweak a bit... and you can always just get a DD-3 for really cheap anyyways.

-Colin

[smoguzbenjamin]

It's a good point that, using a PIC IC for the BBD clock. That would produce a couple of interesting options. I don't know about you guys, but I think I can get my PIC chips burnt at my local electronics shop if I provide them with the code.

I might have to dive into that. No time now, end-of-year exam week coming up... :?

[Nasse]

:shock: Just a thought

I really wonder and it would be interesting to know how many gigging musicians use tap tempo facility on stage. I have one commercially made box that has some kind of sluggish delay and a tap tempo.  It might be me and those small buttons but I think it is quite difficult to adjust delay time precisely with such facility.

I would prefer some kind of display of actual delay time and lots of presets, or even midi tempo syncroniser if I was designing a delay

But that is just a thought

[smoguzbenjamin]

like a numeric X-millisecond delay indicator... good point Might be hard to do though. It'd take up a lot of space, that's for sure. Both on a PCB *and* the box.

Hang on I've got a 2-digit LED display lying around sweeeeeet

[niftydog]

pick the right PIC and you can program it yourself with the help of a serial port, two or three resistors and a diode.

Check out //www.microchip.com and look for ICSP (in circuit serial programming.)