Simple sine and square wawe generator - Page 1
Forum section: electronics / beginners

author: robimarko
author_rank: Regular Contributor
timestamp: May 20, 2014, 08:43:10 pm
content: Hi everybody,I really need simple function generator that can generate sine and square wawe.Please help me

author: grumpydoc
author_rank: Super Contributor
timestamp: May 20, 2014, 09:01:52 pm
content: http://images.lmgtfy.com/?q=simple+function+generator+that+can+generate+sine+and+square+wave

author: benjamin545
author_rank: Contributor
timestamp: May 20, 2014, 09:23:41 pm
content: something like this?http://www.amazon.com/Elenco-1MHz-Function-Generator-Kit/dp/B0002MQEW4/ref=sr_1_2?ie=UTF8&qid=1400620975&sr=8-2&keywords=elenco+function+generator

author: robimarko
author_rank: Regular Contributor
timestamp: May 21, 2014, 04:08:39 am
content: I am more of DIY guy

author: TVman
author_rank: Frequent Contributor
timestamp: May 21, 2014, 05:19:59 am
content: Quote from: robimarko on May 21, 2014, 04:08:39 amI think it is A DIY kit.

author: Bored@Work
author_rank: Super Contributor
timestamp: May 21, 2014, 05:22:43 am
content: Quote from: robimarko on May 20, 2014, 08:43:10 pmSo when you googled, which potential candidates (schematics, kits, products) did come up?

author: Riotpack
author_rank: Regular Contributor
timestamp: May 21, 2014, 05:28:26 am
content: Maybe build something based on the old XR2206www.jaycar.com.au/images_uploaded/xr2206v1.pdf

author: robimarko
author_rank: Regular Contributor
timestamp: May 21, 2014, 06:58:47 am
content: Then I will have to order XR2206,I thought maybe there is one version that i can build with components that I have at home

author: LvW
author_rank: Frequent Contributor
timestamp: May 21, 2014, 07:06:57 am
content: Quote from: robimarko on May 20, 2014, 08:43:10 pmWhat does this mean? Sine and squarewave at the the same time ? Or alternating (selectable per swirch)? Which frequency? Tunable (this is most important)?Why not using a simple RC oscillator (WIEN type or simlar) with additional limiting (clipping)?

author: robimarko
author_rank: Regular Contributor
timestamp: May 21, 2014, 07:19:20 am
content: Quote from: LvW on May 21, 2014, 07:06:57 amOf course not in the same time,selectable with swich.Tunability is not so important.I will try wien bridge oscillator

author: LvW
author_rank: Frequent Contributor
timestamp: May 21, 2014, 08:59:56 am
content: Quote from: robimarko on May 21, 2014, 07:19:20 amPerhaps this choice can meet your requirements - perhaps not?Do you have some particular requirements regarding frequency, amplitudes and quality of the signals?These information are important for selection of a suitable principle.

author: rdl
author_rank: Super Contributor
timestamp: May 21, 2014, 09:19:12 am
content: You can build a rudimentary function generator from some op amps and a handful of resistors and capacitors. Try Googling "op amp function generator circuit"

author: robimarko
author_rank: Regular Contributor
timestamp: May 21, 2014, 09:30:31 am
content: I have no special demands,only that signal is decent quality,5V amplitude would be perfect,as for frequency I have no specific demand,any frequency will be fineSent from my IOCEAN X7 using Tapatalk

author: LvW
author_rank: Frequent Contributor
timestamp: May 21, 2014, 11:32:08 am
content: Quote from: LvW on May 21, 2014, 07:06:57 amI think, I should better say ".....with an additional comparator".

author: tszaboo
author_rank: Super Contributor
timestamp: May 21, 2014, 11:52:28 am
content: Quote from: robimarko on May 20, 2014, 08:43:10 pmI need to chose a small resistor. Please help me.We can only help if you can describe what you really want. Speed. Size. Peak to peak voltage. Price.Give us at least some basic specification, otherwise we cannot help.

author: robimarko
author_rank: Regular Contributor
timestamp: May 21, 2014, 12:06:07 pm
content: Quote from: NANDBlog on May 21, 2014, 11:52:28 amI need this generator for capacitance measurement with oscilloscope.I think that 5V peak to peak will be fine and a frequency of 100kHz.It would be great if price is around 10 dollars.

author: jpb
author_rank: Super Contributor
timestamp: May 21, 2014, 12:31:12 pm
content: Why not just use a 555?http://www.555-timer-circuits.com/simplest-555-oscillator.htmlyou can get the sin from the square wave with a low pass filter I guess.

author: tszaboo
author_rank: Super Contributor
timestamp: May 21, 2014, 12:53:46 pm
content: Quote from: robimarko on May 21, 2014, 12:06:07 pmVery good! The 555 mentioned above is perfect for this application.What I would do is the following: Make a 555 circuit, astable multivibrator, size it to around 100Hz-1Khz. It doesnt have to be 50%, close to it is fine. Power it from a 9V battery. That is cheap, easy, works untill the battery dies. Put a resistor on the output, or even better, a potentiometer, maybe even logaritmic pot.Connect the ground and the output on the unknown capacitor. Measure the voltage across the capacitor with the scope.Now, look at the scope plot. You will see the capacitor beeing charged throug the resistor, than discharged. At around 0% charge and 66% charge put the markers on the scope. The time between the two will be the theta, the time constant of the RC circuit. You can measure the R with a multimeter, and you can calculate the C. This is a very educational circuit, this is basically how I did it in high school (with analog scope because they rulez)

author: robimarko
author_rank: Regular Contributor
timestamp: May 21, 2014, 12:59:51 pm
content: Quote from: NANDBlog on May 21, 2014, 12:53:46 pmExcellent idea,will definitively try it.I will do this with analog scope.Most definitively bang for a buck