Electronics SIG meeting Thursday 21st November 2024 at 8pm UK time

[Graeme Dunbar]

Our next meeting is on Thursday 21st November at 8pm.


Join Zoom Meeting
https://us06web.zoom.us/j/81551246421?pwd=3ieafkJye3b0IOHbALxGVOv88IVLYX.1

Meeting ID: 815 5124 6421
Passcode: 787098

[Dave Cooper]

Hi All,

Just wondering if anyone could recommend a good signal generator for my winter electronics projects ? Frequencies mainly audio range but higher would be a nice extra. Sine, square, triangular waveforms etc...A kit with a good reputation would also be fine.
Cheers,
Dave

[Graeme Dunbar]

Hi All,

Just wondering if anyone could recommend a good signal generator for my winter electronics projects ? Frequencies mainly audio range but higher would be a nice extra. Sine, square, triangular waveforms etc...A kit with a good reputation would also be fine.
Cheers,
Dave

I think the choice depends on how much you want to spend, or more realistically what specifications you looking for. On the RS Components and Rapid Electronics websites they start at about £150 which should cover just about any general electronics usage and go up to the several thousands of pounds.

At the extreme budget end there seem to be plenty of options. This is a good video in that it shows what you get (and don't get) at the very bottom end.

I suspect you start getting "real" function generators at around about the £50 mark, e.g. Banggood signal generator

Although it seems very limited in what it says about specifications.

[Dave Cooper]

Thanks Graeme. I'll have a look.....maybe, spend a bit more and get a quality item....?
Dave

[Graeme Dunbar]

Thanks Graeme. I'll have a look.....maybe, spend a bit more and get a quality item....?
Dave

There seems to be a lot of choice around the £150 price mark. I guess it would take a fair bit of hunting around to compare accuracies, sinewave purity and so on. CPC seem to have a good selection.

https://cpc.farnell.com/w/c/test-equipment/signal-generators-signal-analysers/signal-generators?CMP=KNC-GUK-CPC-PMax-17494878465-&sort=P_PRICE

A good quality "old fashioned" sine, square, sawtooth and triangle generator seems to cost as much as more modern "arbitrary waveform" generators.

There are some sub-£100 ones from the far East that look like they might be the "real thing". Whether I'd take a gamble on them being OK or pay the extra to let someone else look into the specifications and quality I'm not sure. If there were reliable direct comparisons online I might.

On the other hand I'm intrigued by the ultra-cheapo one just as a little soldering practice and a handy source of signal to go in a toolbox. At a couple of quid it is tempting!

https://www.aliexpress.com/item/32981165924.html?src=google#nav-specification

The kit is less than the bare IC! https://cricklewoodelectronics.com/XR2206CP.html?gad_source=1&gclid=CjwKCAjw68K4BhAuEiwAylp3knCdMcwNg1zbT3-QWOZqbM4FMVbTRkjhqSuS5EOaL-fg4vhCSycExRoCt70QAvD_BwE

I guess the XR2206CP is the modern equivalent of the old 8038 that Maplin and others used to sell.

[Hugh Norwood]

Looks like you would really require an oscilloscope to determine what output you get from that Aliexpress one!

[Brandyman]

Thanks Guys,
Since last Thursday I have purchased a budget Scope a budget signal generator and almost a bench power supply, until I remembered I already built one out of a PC unit. Oh and a new motor from Tramfabriek,
I did stop myself buying a Lego trainset for my Granddaughter's birthday, but only because I know she would not let me play with it.

Jeff Sydenham

[Dave Cooper]

Apologies for missing last night's meeting. Bit of a clash on the 'social calendar !'

I've now got my 'scope working, Tektronix T912 vintage, and the CRT /triggering /memory store still working reasonably well.

Modelling wise : currently, experimenting with some home-made 009 couplings using 'mini-size' paper clip wire. (Some success and some failure !).
Standard gauge - successfully converted a bit of test track from 00 to P4, and an old Triang /Rovex tanker re-gauged to fit on same. (Much faffing with wheelsets though). Also, fitted better wiring and choc strips to assist under layout board electrics for the mixed gauge crossing.

Look forward to reading other's notes, Cheers,
Dave

[Dave Cooper]

With my newly found 'scope skills (Ha !), I'd like to start experimenting with Sine, Triangular, and  other useful waveforms. I have Arduino-type breadboards, conventional components plus the odd chip or, two.

Can anyone suggest some suitable 'starter' circuits, together with any specialist chips that may be needed (quad op-amps etc.) ? Main applications are DC motor control and guitar special effects....

Thanks for any advice,
Dave

[Graeme Dunbar]

With my newly found 'scope skills (Ha !), I'd like to start experimenting with Sine, Triangular, and  other useful waveforms. I have Arduino-type breadboards, conventional components plus the odd chip or, two.

Can anyone suggest some suitable 'starter' circuits, together with any specialist chips that may be needed (quad op-amps etc.) ? Main applications are DC motor control and guitar special effects....

Thanks for any advice,
Dave

Hi Dave,

Perhaps a good device to include would be 555 timer and some the oscillator circuits.
http://www.sophphx.caltech.edu/Physics_5/Data_sheets/555appnote.pdf

There will be some interesting waveforms at various points in the circuits as can be seen from the applications note. There are also plenty of 555 tutorials on YouTube and elsewhere.

There are also YouTube channels for building DIY guitar pedals. There is a good one that I have not found yet in my viewing history by someone who teaches on an electronic music course, but here is another one.

In our Zoom calls we have discussed creating a repository of model railway controller circuits. Perhaps we should look more closely at this.

Edit:

Found it. Not a circuit building channel, but it goes into the background of various aspects of guitar electronics. There is a fair bit of heavy going, but some parts stand watching as individual videos, e.g.

I'll try to add more "on topic" material for model railway controllers!

[Dave Cooper]

Thanks Graeme,

Looks like that will get me off the starting blocks.....I'll get a small stock of '555's in as well. I think they'll probably have a multitude of uses!

Cheers,
Dave

[Graeme Dunbar]

There are plenty of model railway related circuits that can be built using 555s.

This is an old web site, but plenty of circuits to browse
https://www.talkingelectronics.com/75/75.html

[Hugh Norwood]

Just a note - use the 7555 rather than the 555. It is an upgraded version based on CMOS technology that addreses a lot of the issues with the original 555 (which, after all, is, what, 50+ years old?)

(I use the 7555...)
It is a drop-in replacement. (oh yes - I always use IC sockets, too!)


P.S. I shall get the notes of the meeting typed up... <grin>

[Dave Cooper]

Thanks Hugh,

I was planning to put a component order in next week. I'll now include 7555's and matching sockets. I usually use "Switch Electronics" - reasonable prices and good service...

Cheers,
Dave