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DIY Stompboxes => Building your own stompbox => Topic started by: Nyklus on June 12, 2013, 09:30:15 PM

Title: Found this circuit, what can i make out of this?
Post by: Nyklus on June 12, 2013, 09:30:15 PM
it says opamp function generator
says sine triangle and square wav on the circuit
and also
has a
LM348N ic chip in it.

(http://25.media.tumblr.com/3c0f3de4e319059fb7af027bcb805591/tumblr_mob5bfJbrH1sn9smpo1_1280.jpg)

(http://25.media.tumblr.com/3609e0559584ddc820dcfb668d2a9c8a/tumblr_mob5bfJbrH1sn9smpo2_1280.jpg)

(http://24.media.tumblr.com/4fe80f1fbbcb88e57abbe1cbbb830358/tumblr_mob5bfJbrH1sn9smpo3_1280.jpg)
Title: Re: Found this circuit, what can i make out of this?
Post by: artifus on June 12, 2013, 09:35:47 PM
Quotewhat can i make out of this?

at least one post consisting of a few pretty pictures posted on diystompboxes.com.

google function generator and follow that trail. read the app notes from ti et al. good luck and have fun.
Title: Re: Found this circuit, what can i make out of this?
Post by: Nyklus on June 12, 2013, 09:47:55 PM
what is ti  et al?
Title: Re: Found this circuit, what can i make out of this?
Post by: PRR on June 12, 2013, 09:54:20 PM
It's a signal-generator for testing your builds.

This one seems to originate at Kitsrus but is better documented at PAiA K23 (http://www.paia.com/proddetail.asp?prod=K23).
Title: Re: Found this circuit, what can i make out of this?
Post by: artifus on June 12, 2013, 09:58:31 PM
Quote from: Nyklus on June 12, 2013, 09:47:55 PM
what is ti  et al?

ti = texas instruments. they design and make chips and stuff and publish papers about them. other manufacturers do too.
Title: Re: Found this circuit, what can i make out of this?
Post by: Thecomedian on June 12, 2013, 10:37:59 PM
You can find a circuit to turn that triangle wave output into a sine wave output, for starters. Then you can test your pedals putting through different frequency sine waves.
Title: Re: Found this circuit, what can i make out of this?
Post by: Nyklus on June 12, 2013, 10:51:23 PM
oh i just found out that it can only make one frequency
Title: Re: Found this circuit, what can i make out of this?
Post by: Thecomedian on June 13, 2013, 12:00:16 AM
so you'll need a circuit that can turn that frequency into higher or lower frequencies.
Title: Re: Found this circuit, what can i make out of this?
Post by: armdnrdy on June 13, 2013, 12:45:44 AM
Quote from: Nyklus on June 12, 2013, 10:51:23 PM
oh i just found out that it can only make one frequency

Not sure where you got that info.

In the pictures you posted of the function generator, you'll see a round black thing with an orange cylinder coming out of the center.....This is a potentiometer. This controls the frequency.

You can vary the frequency and wave with a function generator. If it had a fixed frequency it would just be called an oscillator.
Title: Re: Found this circuit, what can i make out of this?
Post by: PRR on June 13, 2013, 01:31:07 AM
> Not sure where you got that info.

I don't think anybody reads anymore, not even words on pictures (it's already GOT a sine).




> You can vary the frequency and wave with a function generator. If it had a fixed frequency it would just be called an oscillator.

Many oscillators vary frequency. The classic Fender tremolo oscillator, the H-P 200AB, the LO in classic radios.

The academic in me is bothered calling this a "function generator", but the useage is widespread.

Oscillators cover a w-i-d-e spread of techniques. The simplest kind have to "build-up". Another kind works with ramps and voltage detectors, always starts-up full level. Either can be vari-freq.

Simple oscillators make near-sines. The sine can be super-good but not perfect.

Ramp-based ocsillators tend to ramp-wave or triangle-wave, with a square-wave at the other side. A true Function Generator can convert the triangle to a Sine. (Here they use diodes to generate a LOG function which is pretty-close to a Sine function and a heap cheaper.)




All this board needs is a battery, an output cap, and possibly an output volume control (it makes Volts of signal and guitars make part-Volts).
Title: Re: Found this circuit, what can i make out of this?
Post by: Thecomedian on June 13, 2013, 03:20:55 AM
heh, prr. you got me, I was 24 hours too tired.
Title: Re: Found this circuit, what can i make out of this?
Post by: Nyklus on June 13, 2013, 05:59:44 AM
can i plug my guitar into it?
Title: Re: Found this circuit, what can i make out of this?
Post by: Thecomedian on June 13, 2013, 06:11:23 AM
it'd be the same as plugging one guitar into another guitar. they both produce voltage waves. There is no "input" for it, so you'd have to figure out how to build one in and keep the circuit working as intended, but why would you want to do this?
Title: Re: Found this circuit, what can i make out of this?
Post by: merlinb on June 13, 2013, 06:18:05 AM
Quote from: Nyklus on June 13, 2013, 05:59:44 AM
can i plug my guitar into it?

This sounds like a wind up, to me..
Title: Re: Found this circuit, what can i make out of this?
Post by: Paul Marossy on June 13, 2013, 11:55:44 AM
Use it to make a ring modulator?
Title: Re: Found this circuit, what can i make out of this?
Post by: Nyklus on June 13, 2013, 03:02:35 PM
hey paul have any leads on HOW to make this into a ring modulator?

Where would i plug in?
Title: Re: Found this circuit, what can i make out of this?
Post by: Paul Marossy on June 13, 2013, 04:10:17 PM
Quote from: Nyklus on June 13, 2013, 03:02:35 PM
hey paul have any leads on HOW to make this into a ring modulator?

Where would i plug in?

It would replace the oscillator section of the schematic here: http://experimentalistsanonymous.com/diy/Schematics/Ring%20Modulators%20and%20Frequency%20Shifters/Maestro%20RingMod.gif

Not a simple project though. But true ring modulators are a lot of fun to play with (for me).
Title: Re: Found this circuit, what can i make out of this?
Post by: armdnrdy on June 13, 2013, 04:59:00 PM
Quote from: Nyklus on June 13, 2013, 03:02:35 PM
hey paul have any leads on HOW to make this into a ring modulator?

Where would i plug in?

It seems as if you are very "Gung Ho" at wanting to mod something. It would be verging on the ridiculous to modify a function generator into a ring modulator when there are plenty of ring modulator projects ready to build.

You seem to be full of ideas for modifications but lack the knowledge to implement them. IMHO you are putting the cart before the horse!
My advise is to build a few pedals first. This will get you acquainted with schematics, data sheets, board layouts, and different components.
This site is loaded full of invaluable information as is the internet. These are great tools.....use them.

A great beginning step to modification is to study similar circuits to see how it can be implemented in the circuit you want to modify. Studying the circuit will help you understand what it is doing which in turn adds another piece of electronics knowledge.

If you just want to come up with ideas and post a thread asking someone else to design the circuit for you won't learn very much.

Once again....My advise is to build a few pedals!
Title: Re: Found this circuit, what can i make out of this?
Post by: artifus on June 13, 2013, 05:09:06 PM
a good get you going read for gung ho noobs: http://loliel.narod.ru/DIY.pdf (http://loliel.narod.ru/DIY.pdf)
Title: Re: Found this circuit, what can i make out of this?
Post by: Paul Marossy on June 13, 2013, 05:47:08 PM
Quote from: armdnrdy on June 13, 2013, 04:59:00 PM
It seems as if you are very "Gung Ho" at wanting to mod something. It would be verging on the ridiculous to modify a function generator into a ring modulator when there are plenty of ring modulator projects ready to build.

Well, not so ridiculous to me. There is one ring modulator that is like a modified Maestro RM out there that uses a bona fide function generator chip for the oscillator section instead of the original arrangement shown on that schematic. But I agree, it's kind of a lot of work to graft it into a circuit like that. Certainly not something for a beginner to even think about. But the question was asked....  :icon_wink:
Title: Re: Found this circuit, what can i make out of this?
Post by: PRR on June 13, 2013, 11:18:19 PM
I think a basic audio signal source is *vital* for audio testing and experimentation. If I didn't already have several such gizmos handy, I'd use that one. But maybe I been doing this too long.
Title: Re: Found this circuit, what can i make out of this?
Post by: armdnrdy on June 14, 2013, 12:35:48 AM
Quote from: PRR on June 13, 2013, 11:18:19 PM
I think a basic audio signal source is *vital* for audio testing and experimentation. If I didn't already have several such gizmos handy, I'd use that one. But maybe I been doing this too long.

I completely agree....you have been doing this too long!  ;D

Seriously, Early on, I saw the need for certain test equipment. Service manuals for flangers and delay units that include factory calibration and set up procedures call for inserting a sine wave of a specific frequency and amplitude to calibrate bias, feedback, ect.

You can't do that strumming a guitar. 
Title: Re: Found this circuit, what can i make out of this?
Post by: merlinb on June 14, 2013, 05:45:27 AM
What the OP's question reminds me of:
(http://i.imgur.com/i0v31Q3.jpg)