NOT re-inventing the 'Electronic' Wheel !! - Page 1
Forum section: electronics / general

author: GlennSprigg
author_rank: Super Contributor
timestamp: June 29, 2020, 12:51:00 pm
content: MOST of us 'hobbyists' have/useBudgetequipment, as opposed to some of the Professionals here.I for one, am starting again in my old age, after loosing all my test equipment many decades ago !!A LOT of us (?)may/dohave such cheap devices like the "FG-100 DDS Function Generator", for $24 !As an example, that's all cute, well & good! However, some of us want say 'Amplitude-Modulation' aswell, amongstotherthings! Well, if you are working on old radios etc, and want to tune 'IF' (intermediatefrequencies like 455-khz etc), then you can pay many hundreds if not thousands of dollars for specializedtest-equipment. So for justONEexample, how can we simply add 'Amplitude-Modulation' to our signal!?I reviewednumerousmethods, involving relatively complex circuit designs, until I found out about the...AD633 Chip!! It's all done for you!!!....This is butONEof it's functions/uses(modes), requiring virtually NO other circuitry! The above image wastaken from the Spec/Data sheet for that chip, which varies from about $1 to $2. Spec-Sheet...https://www.tme.eu/Document/ce5356ac4efb480c752b9e53289e2634/AD633ARZ-Analog-Devices.pdfInput your 'Modulation' tone, (or voice!) along with the 'Carrier' and you are home & hosed!!See the likes of....for a simplistic demo. I need to stop reinventing the wheel, and use such simple & cheap devices, inconjunction to what I have, without needing lots of money!!With just a LITTLE bit of fore-thought, we can do SO much more, with what we have

author: tom66
author_rank: Super Contributor
timestamp: June 29, 2020, 12:53:27 pm
content: Interesting. But there are simpler ways with not too much expense. My £60 FY6800 supports AM and FM modulation too, which can either be input through an external terminal (VCO) or generated internally. My GW Instek AFG-2105 also supports this. This is a common feature on many signal generators, as you point out it is commonly needed.

author: GlennSprigg
author_rank: Super Contributor
timestamp: June 29, 2020, 01:03:48 pm
content: Quote from: tom66 on June 29, 2020, 12:53:27 pmI think I am aiming this at people with basic cheap equipment at hand, and how easy it is tomodify for more advanced features. Cost, being the main point. Thank you !

author: RJSV
author_rank: Super Contributor
timestamp: July 26, 2020, 01:02:29 am
content: Hi there, I also enjoy evaluating cheapo solutions, although I (barely) can afford $35 parts orders now and then.For a high speed signal, a 'drug store's toy hand-held video game can provide signals. Complex audio but also if you can isolate a high impedance probe there will be a HF clock found on the crystal. You can cut away portions of plastic case. Crystal might only provide low voltage etc. Expect 8 ,MHz, maybe.You get a case / speaker / battery holder / power switch. AND my favorite 'slogon': "You get a couple of free batteries, in the deal.P.S. Steer clear of the 'educational' toys: often they have keyboard integrated into the case front.Ages 3+, that'd be me!

author: ebastler
author_rank: Super Contributor
timestamp: July 26, 2020, 08:36:57 am
content: Glenn -- where did you see the AD633 for $1 to $2? Wherever I look it is more than $10. By the time you have it powered, added input/output amps, connectors, power supply... it will easily have cost you $30.Also, your suggestion to add an AD633 to an existing single-channel signal generator seems to be lacking the second channel? Wouldn't you want one channel to provide the carrier, and a second channel to provide the modulation signal in most applications?I am with tom66 here: You might want to consider starting over with a dual channel signal generator. Even a low-cost one like the FY6800 will give you much more functionality, and a much handier package, than a homegrown add-on to a single channel unit.

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 27, 2020, 02:43:21 am
content: A $5 fl2k adapter will generate 3 arbitrary signals at up to 70MHz or so, or higher if you pick off the harmonics using a bandpass filter instead of lowpass.