Simply Function Generator - Page 1
Forum section: electronics / beginners

author: TorqueRanger
author_rank: Frequent Contributor
timestamp: February 01, 2013, 12:41:54 pm
content: I was checking out a battery operated function generator on YouTube and it is a really simple design ... But my question is are they useful for anything or a waste and would you suggest that I build??? I am trying to build a useful function generator that I Can build on a breadboard and i am using a bk precision 2120 20mhz scope.

author: kripton2035
author_rank: Super Contributor
timestamp: February 01, 2013, 01:14:19 pm
content: a simple ne555 with a single potentiometer is already a nice useful function generator IMHO ...

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 01, 2013, 03:44:30 pm
content: Quotewhat battery's voltage? single or dual battery (as in bipolar supply). whats the price? whats the output level and impedance? all in all, do you have spec info or link for the said FG?Quoteit depends on the answers for the above questions... but a decent speced battery operated FG should be handy. imho.Quotea useful FG should be at least on a fixed pcb and traces, if not with exclosure and output jacks. alas it will depend also on your soldering skillmy 2cnts.otoh: my diy FG is using AD9850+opamp in an enclosure using ±12V supply. should be possible using 2x 12V small LA batteries if portability is an issue. ±6V for even lighter and smaller LA if the max 10-12V voltage output is not that critical. YMMV.

author: TorqueRanger
author_rank: Frequent Contributor
timestamp: February 02, 2013, 02:17:43 am
content: Quote from: Mechatrommer on February 01, 2013, 03:44:30 pmWell it runs off one 9v battery and here the link for the build....(http://lib.store.yahoo.net/lib/webtronics/kit23.pdf)Quote from: Mechatrommer on February 01, 2013, 03:44:30 pmIt would be nice to have a nice battery function generator but my build doesn't have to be battery operator...Quote from: Mechatrommer on February 01, 2013, 03:44:30 pmRight now I don't have a way to etch my own boards and my skills with soldering is pretty good ..Quote from: Mechatrommer on February 01, 2013, 03:44:30 pmCan I get pics and schematic for your build ??

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 02, 2013, 03:37:48 am
content: Quote from: TorqueRanger on February 02, 2013, 02:17:43 ami cannot get access to it since... "503 Sorry, Service Temporarily Unavailable"Quote from: TorqueRanger on February 02, 2013, 02:17:43 amerrpp... i forgot to mention, it required mcu programming to send command to the AD9850 if you dont mind that (i can provide the hex file if you use the same chip atTiny13A)...fromhttps://www.eevblog.com/forum/projects/ad9850-module-and-dds3x25-dds-based-fg-compared/i dont claim it to be good (but works for me and my half-retarded brain) in fact it drifts all over (mainly voltage offset since my psu is crappy as well) using proper constant current zener should give you better result. i'm sure you can find many diy FG in the net and here. dave also has schematics for it but i believe the chip is obsolete. some also swear by the analog wien-bridge? oscillator. but then, i cant access your pdf link hence cannot judge fairly, and other people are more expert than i am. everything should converge to... "how affordable it is? and what spec you required? and for what purpose?"Quote from: TorqueRanger on February 02, 2013, 02:17:43 amok now i saw the opening screen of the youtube video, that seems promising but i dont know i havent watch my net is slow. fixed pcb i meant including that perf? board shown. anything should be ok except "solderless breadboard".my 2cnts hope it helps. cheers.

author: TorqueRanger
author_rank: Frequent Contributor
timestamp: February 02, 2013, 11:29:57 pm
content: Here is the website and I can't program for my life lol..http://www.circuitspecialists.com/kit-23.htmlQuote from: Mechatrommer on February 02, 2013, 03:37:48 amI also was checking these too1Hz to 2MHz Function Generator Kit with XR2206http://www.electronics-diy.com/function-generator-kit-xr2206.phpDIY Simple Signal Generatorhttp://www.overunity.com/6857/diy-simple-signal-generator/#.UQ2d_GdxlB0

author: TorqueRanger
author_rank: Frequent Contributor
timestamp: February 03, 2013, 10:28:26 pm
content: This might be a really stupid question but I know with digital function generators they show what you are putting out but how do you know what an analog function generator is giving out?

author: SeanB
author_rank: Super Contributor
timestamp: February 03, 2013, 10:37:23 pm
content: Connect it to a scope?Otherwise use a spectrum analyser and do the reverse of Fourier transform and add up the harmonics to reconstruct the original.

author: PA4TIM
author_rank: Super Contributor
timestamp: February 04, 2013, 12:13:42 am
content: The frequency reading of a digital one is as good as the refrence of the counter build inside. And that is not always great but i can be super. On the other hand, a good analog meter ( an HP or so) can also be very accurate.But there could be other things important like min en max voltage, frequency range, Ofsett voltage, THD, resolution in voltage and frequency setting, in/outputs ( like sync, trigger).Linaerity of amplitude over freuency range, ristetime and fall time of pulses/square. Adjustable duty cycle, sweep output, stability ect.If you want to build and learn, and something like -10 to +10 is enough; see the CA3041 ( or 3140 allway mix them up) datasheet or apponote.This is a cheap opamp and they made a function generator with it that does square, sinewave en triangle ( witch is very easy with opamps)I made a 10000 to 200000Hz squarewave with a comperator and 4013 devider ( 5V 50 % dutycycle for my esr meter)A triangle and square for an active load, a sinewave and sawtooth for a signal generator and pectrum analyser, also opamps , a stepgenerator with a UJT and a low THD sinewave generator with a few more ( app note from LT about bridge measurements from Williams, a adjustable very low THD sinewave oscillator. All very easy to build, just combine them in a cabinet with some switching or use a separte bnc for each output. Best to make an output amplifier too.To complex ? Buy an old Philips, HP, Tek or whatever. Cheaper an will perform better. Or use a DDS and do some programming.