Function generator circuit for beginner - Page 1
Forum section: electronics / beginners

author: winnie
author_rank: Newbie
timestamp: May 19, 2020, 03:54:46 am
content: Am looking to build a FG that will allow me to test and build circuits. I came across a Function generator circuit in internet -https://www.gadgetronicx.com/improved-diy-function-generator/which seems to be tested out and delivers Triangle, Square and Sine wave output. I am going to try this one out soon but before that I was thinking is there any other DIY FG circuit which is much simpler in terms of construction than this one. It's just that this circuit seems to use lot of components and thought to see if I have any other options.

author: WattsThat
author_rank: Frequent Contributor
timestamp: May 19, 2020, 04:55:48 am
content: That’s a fairly crude device with rather limited usefulness (and no specs), it all comes down to what you need it to do. Setting the frequency range with a dip switch will get old pretty quickly.If you’re just looking to build something, by all means give it a go and have fun but don’t expect a decent return on your time investment. Alternatively, there are cheap kits on eBay (~$10) based on the XR2206 FG chip that would probably be just as good, maybe better with less time and money spent.If you want a bench unit that can provide some useable life and get you through more than basic beginners stuff, there are some inexpensive units out there, the 20 MHz FeelTech can be had for $50-$60. They are certainly worth a look if you can afford it.

author: winnie
author_rank: Newbie
timestamp: May 19, 2020, 09:45:37 am
content: Thanks for the advice $60 sounds really affordable I always thought FG will cost hundreds of dollars. But anyway am not eliminating the circuit option, sounds fun to build own FG, I might give it a go if I have time and patience for it.

author: themadhippy
author_rank: Super Contributor
timestamp: May 19, 2020, 01:18:32 pm
content: This little circuit has served me well for years,unfortunately the main chip is no longer officially available,but theirs plenty of clones on ebay

author: Kleinstein
author_rank: Super Contributor
timestamp: May 19, 2020, 06:17:21 pm
content: Quote from: winnie on May 19, 2020, 03:54:46 amThe circuit looks not so bad. For real use one may consider an additional amplifier at the output to get more amplitude. It is similar to the internals of the old FGEN chips (XR2206, ICL8038) that are no longer available - though there seem to be some Chinese clone of the XR2206. Moden Fgens usually go the DDS way. This gives much better frequency stability, though with some weakness for the triangle.

author: Picuino
author_rank: Super Contributor
timestamp: May 19, 2020, 08:37:59 pm
content: You can buy one from ebay.https://www.ebay.com/itm/XR2206-Function-Signal-Generator-DIY-Kit-Sine-Triangle-Square-Wave-9-12V-DC-CAO/332938708031?hash=item4d84b1843f:g:63UAAOSwnKFcDdNTOr better:https://www.ebay.com/itm/DDS-Function-Signal-Generator-Module-Custom-Arbitrary-Waveform-Sine-Triangle/261544466047?hash=item3ce543d67f:g:krkAAOSwaOxZrpo5https://www.ebay.com/itm/JDS6600-60MHz-Signal-Generator-Dual-Channel-DDS-Function-Waveform-2-4-Display/283866721763?hash=item4217c66de3:m:m-InUdYyJki9kUwm8MtF_3w

author: wizard69
author_rank: Super Contributor
timestamp: May 20, 2020, 06:06:49 pm
content: Do you have a specific need here? As a beginner you probably don't need a lot of capability thus should avoid spending a lot of money on a function generator. Thankfully you can find a lot of used equipment which means more capability for the dollar. If you want dirt cheap you can get items like this:https://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10001&productId=2279543&catalogId=10001&langId=-1&CID=GOOG&gclid=EAIaIQobChMI8uG5qIDD6QIVD47ICh0mrQr9EAQYAyABEgK4ZfD_BwEfor under $40 bucks cheap. The quality and capability go up from there for an assembled unit. Get on Banggood and you get access to all sorts of low cost solutions including board only kits.Quote from: winnie on May 19, 2020, 03:54:46 amThat ins't a complex circuit considering what it does. As others have pointed out there are single chip function generator implementations but they still require external components. So you don't see a huge reduction in complexity.If you don't need sine waves you can program any number of microprocessors to generate square waves and pulse trains. You may find your self needing something along the lines of a pulse generator more than a sine wave generator.QuoteIf that bothers you buy something preassembled or buy a kit. The other good option is to go with a used instrument, however be careful. I say be careful because used sometimes has a very hard time beating the low cost new Chinese imports.