XR2206 DIY signal generator kit.

Terry01

Jul 5, 2017
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I soldered a wee signal generator EBay DIY kit together today. I've been tinkering about all day with it learning how to get a nice clean trace on my oscilloscope. It puts out square,sine and triangle wave forms from around 20hz to 100 KHz so its been good fun. I think I'll invest in a proper signal generator. Just a cheap one but better than the DIY kit I have. :)
 

shrtrnd

Jan 15, 2010
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You've got the bug.
Don't let your wife know you'll be investing in a new hobby or she'll hide your wallet.
 

Terry01

Jul 5, 2017
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Ha ha! The bug is well and truly set in my friend! I'm having great fun and just keep finding more I want to learn. I only have an analogue oscilloscope though and was wondering if I hook my multimeter up to it along with my scope will I be able to get the frequency readings on the meter along with the wave on my scope? Sorry if this seems a silly question but I'm just starting out. I think it will be ok but I've learned to ask rather than just hook stuff up when I'm not sure. I only have a few fuses left for my meter and they're not cheap! :cool:
 

Audioguru

Sep 24, 2016
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An analog oscilloscope shows time per grid line so simple arithmetic will give the frequency.
When a multimeter is set to show frequency then its input draws almost no current. The fuses in a multimeter blow out only when it is set to measure a current too high for it. Maybe you tried to measure how much current a car battery can produce (600A) to turn over the starter motor when the engine is very cold?
 

Terry01

Jul 5, 2017
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Yes I've had the calculator out already. I was just wondering if a meter would do it to confirm my maths.

I blew out a couple fuses on my Hyelec(cheapo) and ExTech meters plugging the leads in the wrong jacks and forgetting to change to the correct jack when changing the selector etc.
I think I may have been doing everything that was possible to do wrong....wrong!

I am teaching myself electronics and I know zip so it makes for some head scratchers and sometimes funny results. I didn't mind blowing the fuses on my first meter so much but I've bought a couple of decent meters so would rather ask you guys before doing anything I'm not sure of. I didn't even have that luxury at the beginning. I'm learning bits and pieces from YouTube videos and asking on here and its great fun. I lose hours sitting at my bench. Its awesome!

Thanks for the help...Terry
 

kellys_eye

Jun 25, 2010
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Nice to hear of the enthusiasm the hobby generates.

Nothing wrong with making mistakes as you learn too - providing you actually LEARN from them....!

Little bit of advice though - if you feel the hobby is going to 'go somewhere' for you then by all means get those small circuits to 'play with' but consider spending a little more for the 'proper' equipment - even second hand - as you'll just end up wanting to get better and better versions before suddenly realising you've spent more on the itty bitty stuff than it would cost to get a decent one in the fist place!

Been there, done that!
 

Terry01

Jul 5, 2017
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I definitely have intentions of gaining more knowledge of electronics. Learning one thing seems to open up another half dozen things to learn and so on. I'm more of a tinkerer than scientist but think electronics has something to offer both and everything in between. I love too that I can totally suit myself how much I give each time I sit at my bench. I can get right into the numbers of 1 component and really tire myself out on it or I can relax and take a day to solder a wee eBay kit or just test 1 meter against another and compare results for something to do. Its awesome!

My next purchase will probably be a second hand signal generator. I'll spend around £50ish. I've been looking on eBay and can get a new Chinese number or 2nd hand brand name one. I'll do a bit more reading up before I buy though. I understand to a very basic level what they do but also find looking through what's available I find new functions or settings to read up on building my knowledge as I go. I got the wee cheapo to see if I'd like one and I've been tinkering for 2 days now. Its been great!

I'm having great fun with my analogue oscilloscope right now too so I'm going to ask Santa for a digital one for Christmas. I was thinking of getting a 3D printer but I'll put that on hold for now. Maybe into the new year I'll think more about the printer.

There's so much fun to be had! It's great!! :)
 

Audioguru

Sep 24, 2016
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My oscilloscope is 54 years old and I made it as a kit. It is analog and shows a very clear waveform.
Many digital 'scopes show a staircase instead of a smooth ramp or sinewave.
 

Terry01

Jul 5, 2017
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Cool. I often wonder about how many of the new instruments of today will still be doing a good job in say even 25 years. I like watching the videos on people restoring these things. There's something very satisfying about it.
I got my scope from eBay. Its just basic but does everything it's supposed to. Its been great to learn on. I'm well happy with it. When I get a digital scope I'll probably get a new one. I'll probably get a signal generator 2nd hand from eBay too soon though. I dunno why i want new when i get a digital scope. As long as your careful there's some decent buys out there. I can ask on here too which is great. People who know better can keep the new guys right. Its awesome having that guidance.
 

hevans1944

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Jun 21, 2012
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I dunno why i want new when i get a digital scope.
New will usually get you the latest state-of-the-art, which is important with digital oscilloscopes and most other electronics instrumentation available today. But no matter when you buy, realize that it will be obsolete by the time you receive it, replaced by a newer model that is less expensive with better or more features. And made in China.

My main reason for buying a digital o'scope last year, after more than fifty years of being satisfied using a Tektronix analog o'scope, was waveform capture and subsequent persistent display from on-board digital memory. Plus, you can do a "print screen" to include snapshots of captured waveforms in printed communications, such as here on EP. There really is no analog equivalent for this, although analog storage oscilloscopes exist, and have existed, for many years. In fact, I have used analog storage oscilloscopes in the previous century and found them wanting. But when digital storage oscilloscopes finally arrived on the scene they were obscenely expensive. There were two reasons for this: (1) really fast analog-to-digital converters (flash converters) were/are expensive and (2) really fast solid-state memory (RAM) was expensive. Neither reason is valid today to justify selling a digital oscilloscope for tens of thousands of dollars. Only if you have deep pockets do you pay that much to get a "name brand" with extra features or extended bandwidth.

Now is an excellent time to explore the possibilities of a digital storage oscilloscope (DSO), with inexpensive DIY kits readily available from China for about twenty-five bux. A friend here on EP gifted me one of these last year (some assembly required!), and that provided impetus shortly afterward to purchase a "new and improved" factory-built Hantek DSO5202P from Circuits Specialists, on sale for less than $300 with free shipping. This isn't a "top-of-the-line" digital o'scope, but it provides most of what I need in an oscilloscope, for about the same price that I purchased a used Tektronix 465B fifty years ago at the Dayton Hamvention™. Since then, I acquired two more 465 o'scopes, so I really like them. But I also like my Hantek DSO, and the freebie kit 'scope is handy for its totally isolated-from-ground, battery-only, operation... although you can power it from a wall-wart to avoid having to replace or recharge the battery.

So, yeah, welcome to the hobby... try not to buy everything all at once, even if you can afford to do so. Better prices and better performance is always just a few months away because electronics manufacturing has essentially become a production printing operation. Instead of ink and paper, we use chips, SMD and printed circuit boards, all automagically assembled at low cost. New ideas percolate and rise to the top of the sales heap constantly. You will go nuts trying to keep up! So don't try. (Has anyone ordered their new iPhone 8 yet?)
 

Terry01

Jul 5, 2017
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I was looking at the 100mhz option for that scope. Its going here for £220 so thats not bad at all. That and a similar spec Rigol one but the Rigol one seemed to be quite a bit more £££ for the same features. Just over £300! To be honest I wouldn't know the difference and for sure wouldn't need the top of the range of this or that. I'll get that at Christmas time though. I'm on the hunt for a second hand signal generator. I should get a so so one for £50-£75 or there about. Looking forward to that. :)
 

kellys_eye

Jun 25, 2010
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The significant advantage of modern DSO's for me is their ability to automatically measure signals and, on some models, auto decode serial data too. Such facilities are 'just' software - as is the base performance spec of some models (deliberately de-rated in software with Youtube having some clips on how to boost performance by hacking the software!).

Size also matters - although Mrs k_e hasn't ever complained..... (giggidy) - and modern scopes fit the shrinking workshop space far better. Mind, the HEAT from some of the older scopes was essential in winter!
 

hevans1944

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Jun 21, 2012
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I should get a so so one for £50-£75 or there about.
It's good that you set a spending limit for your electronics instrumentation. I have no idea what a "good" signal generator goes for today, but I needed several over the course of some sixty-plus years futzing with electronics. I broadly divide them into two categories: audio-frequency-like and radio-frequency-like, with some overlap between the two.

Usually I am satisfied if the audio-frequency-like signal generators will produce sinusoidal, triangular (sawtooth), and square wave outputs to an upper limit of about one megahertz, and to a lower limit of a a few tenths or a few hundredths hertz. Other bells and whistles, such as variable duty cycle, logic-level outputs, voltage-controlled frequency (VFO), calibrated output attenuation at high and low levels of output, low harmonic distortion, amplitude modulation, yada, yada, yada are also nice to have if they don't exact too much of a premium price. You will have to rely on personal experience to determine what "features" are needed, so be prepared to replace yesterday's treasure with a newer and brighter treasure as you gain experience.

I became interested in radio-frequency circuits at an early age, so for me an RF signal generator was an absolute necessity. I settled for an inexpensive Heathkit version, but there are lots of bells and whistles you can get with RF signal generators.

s-l400.jpg


For me, RF means any frequency above about 10 kHz to several hundred (or even several thousand) MHz. Today you can build a dead-on accurate synthesized RF signal generator with better than one hertz frequency accuracy and resolution. Add an external reference to phase-lock with and you have a "clock" on your bench that won't gain or lose a second... ever! A couple or three GPS satellites is all you need to build your own highly accurate precision oscillator... well, that and a boatload of experience and theory... so it would definitely be "best" to build your first RF signal generator from a published and tested design, and not spend a lot of money on it. Most inexpensive RF signal generators provide only a sinusoidal output, but often with a liberal dose of harmonic content to extend the upper frequency range. Calibrated output signal amplitudes capable of driving 50Ω are useful, but not essential.
 

Terry01

Jul 5, 2017
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Its funny you mention the heat from older scopes. I got mine from eBay. It was a bit of a punt but its turned out to be a good one. When I got it I checked everything as best I could (YouTube videos) and all was fine till I noticed the side was heating up a little. I thought it was bad news but it only warms up a little even when its been on for a few hours. I hadn't seen that before and thought it was curtains for the scope. I'm delighted its going great,I'm still having fun learning on it.
I hooked a meter up across the + and - 9v power lead last night again too! I noticed the second I did it but can't believe I did that. I know better! I never blew anything but was mad at myself. I was looking to see how accurate the Amps display on my PSU was. The PSU said 0.011 A one meter said 12.10xxmA another meter said 12mA too. I love getting my meters out and comparing them. You could say "a bit meter daft that laddie is" LOL!
 

kellys_eye

Jun 25, 2010
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The level of accuracy most people require isn't as demanding as you'd expect. 1% is easily good enough for most amateur work and even cheap meters meet that! There are some spectacularly good meters-for-the-money out there today - so much so that getting three or four and rigging them up in a line makes for a very versatile measurement system.

As you progress 'up' towards more sophisticated projects so the need for accuracy grows - I mean, a 1% error on a HF transmitter circuit is totally unacceptable! and your test equipment purchase will reflect this.

I often see/hear of people having DVMs accurate to 6 digits and 0.001% (or somesuch) but have never actually seen or heard of them USING them to such levels so there is a limit to what is practical for most people.

Of course, if you can purchase a 6-digit DVM for the price of a 3-digit one it's a no-brainer but considering purchasing one????? No. Never - in my life, anyway.

One of the more useful things you can buy (or build) are devices for CALIBRATING test equipment. Such devices are becoming quite common and use readily-available components.

A voltage reference, current reference and frequency reference should cover most needs.

If you know what the error is you can adjust for it - regardless of how accurate your equipment is.

One site I can recommend is:

http://www.scullcom.uk/

where you can find some really useful test equipment and calibration circuit designs as well as information on older test equipment. Very entertaining.
 
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Terry01

Jul 5, 2017
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Awesome site! I'll be spending some time there for sure!

I have 1 of the £5 voltage references you get off eBay. It does 2.5v, 5v, 7.5v, and 10v. I've seen Youtube videos that say the card giving the exact x.xxxV readings they give you with it is mass produced and not specifically for that 1 test unit. Its a "DOH" moment when you think about it. Like the 5v reference is really 4.999v according to the card you get with it. They pretend they've all be checked on some high end bench meter. Like you say though,unless your after scientific results it really isn't a big deal. I just like going through the motions and not seeing smoke to be honest.

I have been looking for a current reference to match though and couldn't find one. Do you know why the voltage and resistance references are plentiful but the current ones aren't? I found that strange. My quest is now over...thank you.

I will pick one of the circuits on the site you gave me and set to building it for myself. I suppose its the next step up for me. I usually just order a DIY kit from eBay and solder it together. Doing one of these I think will help me understand the circuit a bit more.

I have 4 meters now. Nothing really top end but a couple of decent ones and a couple of cheaper ones. That's it though,no more meters. I'll get a signal generator and DSO over the next couple months and that should do me. I'll maybe upgrade a scope or whatever over time but I'm in no rush. If I get as much pleasure out my SG and DSO as I have my analogue scope when I get them I'll be well happy.
 

kellys_eye

Jun 25, 2010
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Awesome site! I'll be spending some time there for sure!
Check out his Youtube channel too - his technical description of the circuitry is very good - a little 'dry' (but that's his way) but overall you can happily sit through a session, no problem.
 

Terry01

Jul 5, 2017
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I will do. I like watching the videos. That's where I learn most of the little I know. Its very handy for someone like me just starting out. I can select what I want to learn and do it whenever it suits me. I even watched a couple of videos on how to work my calculator properly so I can work the calculations out. Its great! There is some questionable stuff too but you've just got to be careful what you listen too. At first I used to just try and take everything in but you soon learn that's not the way to go. Some people put absolute rubbish up and would have you believe its 100% genuine. I have around half a dozen that I refer to now. So far I've been able to find anything I need between them ok.
 
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