Showing posts with label electronic components. Show all posts
Showing posts with label electronic components. Show all posts

2025-08-13

Components, complaints and complacency

Whilst reading a few issues of Wireless World from the world radio museum web site, I wondered about the issue that happened on my 21st birthday month. Reading the editorial rang a very loud bell! If it reads familiar to you enjoy the feeling. JB ZS6WL

We are constantly receiving letters from private individuals who are finding it impossible to obtain supplies of certain components and whose pleas to manufacturers and distributors are met with stony silence. Even the small company, not in the electronics field, which requires a special component for a one-off job—and which has the advantage of a company letter heading—sometimes receives the same treatment.

One of our correspondents, who was starting a small company, claimed he was asked for two trade references and the name of his bankers, and that was only in order to receive a catalogue!

However, component supply is the result and not the cause of the problem, the whole attitude of the electronics industry towards the private experimenter and the amateur is one of non-co-operation to the point of scorn. Why is this, when many of yesteryear’s major innovations in radio and electronics emanated from the results of work carried out on a kitchen table?

In those days the amateur and the professional (often one and the same person) were working on similar problems and there was a mutual respect. The technology has advanced in leaps and bounds since then and industry is staffed with people who more than likely do not have an amateur background and who have no appreciation of the problems and frustrations that can face anyone trying to work on his own for interest, self-education or amusement.

Because of the great amount of publicity given to electronics, and the aura of mystery surrounding it in the eyes of the layman, more people are taking a practical interest. This has led to manufacturers and distributors being bombarded with letters requesting the solution to private electronic problems, many of which are nonsensical or frivolous, and others could have been answered easily if the writer had shown a little initiative or visited a good library.

To answer all these queries would cost a company a great deal and what would they get in return? Perhaps an order for two or three components, the value of which may be less than the cost of the handling.

By making their components generally available on the retail market, to be bought by people who may not be qualified to use them, a company feels that it is inviting the sort of costly correspondence mentioned. The reason for the reticence in this respect can be understood.

All this has led to the present ultra-low status of the amateur in the eyes of industry and the reluctance of many concerns to accept small orders.

The industry does, however, have a responsibility to the public, even if it is only to
maintain its own image, and attempts must be made to give assistance in genuine cases. Refusals because of a couldn’t-care-less attitude can never be justified and small losses should be accepted at times.

Manufacturers could easily set up machinery to ensure that their products can be sold on the retail market through a distributor. Because of the difficulty in assessing the possible quantities required perhaps some sort of sale or return arrangement could be operated with the distributor. At the present time many components are completely unobtainable on the retail market.

In addition, all private individuals seriously interested in electronics should put their own house in order, and as a first step may well think of joining a club. If there is not one in the area—start one. The answer to nearly all the problems likely to trouble the experimenter could be found amongst a group of people with a common aim. Particularly difficult problems could be made club projects. Benefits could be reaped in terms of central facilities, pooled test equipment, tools and literature.

A great deal of useful work can be done by a well-run organisation of this nature and the local community can benefit. For instance, club projects could aid local handicapped people, small electronic systems for local firms could be designed and constructed (power supplies, control systems, photo-electric switches etc.). Often these firms can advantageously use electronic equipment, but, because only a one-off is required, it is uneconomic to employ professionals to do the job.

The companies who supply components would, we feel sure, be more than willing to assist such organisations so long as things were done on a business-like basis. A good example of the sort of co-operation that can be achieved is to be seen in the components list for the Logic Display Aid in this issue.

From: Wireless-World 1969-06 pg69

2025-02-13

RAE Backgrounder 2025-02-13

Some additional notes and musings about the content on the RAE course. 

Resistors 

Resistors nowadays don't have coloured bands or markings. SMDs come on a long tape. They are placed by a numerical controlled XY machine onto printed circuit boards. [Pick and Place machine] Then soldered into place.

Q So why do we make you learn the 'colour code'?

A Well the code values gets used elsewhere. e.g. Cables denoting the number of the wire. Pins 1 to 9. 


A Also you will be able to re-use old resistors for your projects. Most constructors these days re-use or re-purpose old equipment for their projects.

A lot of radio amateurs re-use older equipment to save cost etc. In doing this they need to identify components etc. One example is the conversion of a CB radio to use on the 10 metre band. 

 

Resistor Failings

  • Inductive value [VHF/UHF] - they are measurably inductive.
  • Carbon Composition [very rare] - for non-inductive types.
  • Capacitive value or self-capacitance [VHF/UHF]
  • Power dissipation - heating. [Capacitors do NOT dissipate power]
  • Radiative heat - some resistors come with a heat sink mounting.
  • Volume/Potentiometers - variable resistors used to control the sound output. Log (logarithmic) types are used to vary sound level. But linear types are used for adjustment of voltages or currents. Some are multi-turn for precision setting of voltages/currents.
  • Hair Dryer and Electric Blankets - heat dissipating at high or low levels.
  • FUSES - Where the resistor melts to 'open circuit' and stop the current. This has its own 'issues' as the time to melt has an impact. Higher the current the faster it melts! 

For more information find the informative article "Resistors" in Wireless World 1975-10-01 by R.A. Fairs, B. Sc.

 

Capacitors [Condensers in old docs]

Capacitors have a multitude of uses. "Super Caps" have a very large capacity value and can discharge high currents. Such that some trucks use them to start the engine. Charging from the normal truck battery when not needed.

At radio frequency they provide tuning for resonant circuits or parts of filters.

In pulse circuits they provide delay networks. [Differentiation and Integration]

They can also be used to "tune" an antenna. A "Capacity Hat" on the top of an antenna will reduce the frequency of resonance. Usually used on a short antenna to bring the resonant frequency down.

The majority of electrolytic capacitors get used as "decoupling" capacitors. Or as "coupling" capacitors. But at higher frequencies the ones used are generally ceramic. For filters and resonant circuits mica and air types are used. Being of higher quality and Q value.

For more information find the informative article "Capacitors" in Wireless World 1974-12-01 by R.A. Fairs, B. Sc.

 Both are available on:- https://www.worldradiohistory.com/Wireless_World_Magazine.htm

 

 

2023-04-26

Its Time to Go Back to Basics

So I have been a 'Grumpy [] Man' for a while now. Lots of things tend to annoy me. If it isn't the dog from the back house above us barking, its something else...

Anyway Blogger [this site] has some advantages over the Wordpress site. Especially as it is free. It provides a simple means of getting whatever out there for the rest of the 'internet'. It does not appear to have a limit on storage and it doesn't impact your Google storage either. 

It can of course be accessed from anywhere you have an internet connection. 

Alright it doesn't have the 'social network' aspect built in or applied. Though you can earn cents from adverts on your 'blog'.

I find it so much easier to work with. My jbcs site was 'converted' to Wordpress a while ago by Edith's son. And he left me to upload content into the 'editor'. This proved to be too time consuming for me. I am a retired electronics engineer with a dependent wife. I would take about three-quarters of a day to type and place pictures into the 'editor'. It is NOT a word processor. Which I would have preferred to use. 

My usual 'thing to do' on a monthly basis was to upload the YL News. This did not get done! As I would be always diverted or distracted by something/someone else. 

With Blogger, I can copy and paste text directly and upload pictures. Final corrections and adjustments would take minutes. Sure things tend to jump around on screen. Especially when you have a 'hesitant' connection to the internet. But you can change the settings to suit when you need to.

It does spell checking and auto-saving when you are not typing. You will see a little cloud change to a whirly circle and back to a cloud. A cloud with a slash through it means it didn't manage to connect. It will try again and become a cloud with a tick in it.

There is more to come...


2021-05-24

The Electronics Curse

Many years ago I believe I coined the phrase; "The Electronics Curse." This curse like "Murphy's Law" was used to describe the situation where having designed and constructed some circuit, it was tested. Usually with good results and some application for the time. But with some circumstances beyond my/our control, the circuit would go off into the wild blue yonder.

 

The Curse

"Your amplifiers will oscillate, your oscillators won't!" Often described a new circuit on test that did not come close to working like it should.

Sometimes it was a construction mistake. Carrying the output too close to the input. The short but inductive earth wire was making the circuit 'whistle' at VHF. Or the electrolytic capacitor being connected in parallel with a ceramic capacitor. The designer having forgotten the parallel tuned circuit this creates. Or that the audio amplifier was 'tweeting' (Not the new version) and making a sound like a bird repeating at a regular interval.

This last has triggered my writing this. I have for a long time wanted to re-construct the Direct Conversion receiver from 1968 QST magazine. Using modern 'second used' components. That is a polite way of saying scrounged from junked electronics.

The circuit is this one:-


[You may remember this circuit from The Anode March 2021

Using modern transistors I constructed the circuit of the audio amplifier. Using scrounged capacitors and new(ish) resistors, I built the circuit on Vero like board. This even in the 60's was the quick and easy way of putting a circuit together. Also disliked by R.F. engineers it would provide a path for R.F. feedback of the bad variety. Producing a PC board is out of the question. Cost alone makes this out of the reach or of no interest to most people round here.

What the three transistor circuit was doing, was doing, was oscillating at several MHz. Which was charging/discharging the electrolytic capacitors at audio. 

The resulting 'squawk' was disturbing the cat! I had the output connected to one of the small PC amplified speakers that people threw away.

When I got to the back of the board I found the trace that I had forgotten to cut, was running past the input. So I cut the trace along with a few others for good measure. Switching on, the circuit was quiet. No longer disturbing the cat. And a gentle background hiss said the circuit was sensitive enough to use.

This all is not surprising as modern (1990's) transistors have a much higher transition frequency (FT) than the 1960's ones. So much more gain at VHF and H.F. So a small amount of capacitance and lots of gain add up to instability and oscillation.


So the next step is to place it in a screened enclosure.

The next step in the project is to try out some cores for the mixer. These will have to be 'cheap'! Lets see how the Amidon and Micro-Metals perform vs the old Mullard/Philips types.

 


2021-03-18

Question from the May Rae Class of 2021 - WhatsApp Group

 

The other day I was asked;"@John Brock hi there.. are you able to recommend any simple receiver circuit kits to build ?Just to help me understand some of the fundamentals I'm learning.. some of it is unintuitive."

Pause for thought, yes! But this is not an easy question to answer.

If this were a first world country, I would recommend a 'local' shop to go into and buy a kit.

There are lots of them both kits and shops...

I know because while staying with my daughter in Bristol UK, I ordered stuff and it was delivered to my (sorry her) door the next day!

There were (once upon a time) local shops here on the West Rand and in Johannesburg that sold components. Where hobbyists and Radio Amateurs could buy components or even test gear. Sadly they are long gone since last century.

You can buy kits and components - for a price - and have them delivered by courier. Definitely not the Post Office! But for anyone who is not wanting to spend serious amounts of money, this is not really an option.

The club does have a certain amount of components. Most left to the club after hams going 'silent key'. Some members and other Radio Amateurs sell them off at our regular 'flea markets' / 'boot sales'. I prefer the term 'boot sale' as the other makes you want to bring your own fleas!

Some hams have 'junk boxes' with components and old radios that can be used for new construction projects. I do.

I was going to put a cartoon in here but I did a search for the one sent to me recently. It is from CartoonStock thus has copyright! So no cartoon of an old guy with his son outside the garage saying;"One day son all this will be yours."

To answer the Question

The 'simplest' type of radio useful to a Radio Amateur is a "Direct Conversion" type. In the past I have recommended several designs. All needing components that are getting scarcer by the week.

Recently (in the last few years) I have been component 'scavenging'. This produces all sorts of components. Some basic like transistors and others like PWM generator integrated circuits. Lots of electrolytic capacitors of low and high voltage. These are from 'blown' ATX power supplies used in personal computers. One good Highveldt storm and the power supply is 'dead'! As it is always connected to the mains supply.

So here is a circuit from last century. In fact QST 1968. It has been built by many Radio Amateurs and it does not require 'fancy' components.

It doesn't say a lot of things but you get the general idea from the blocks. Using 'scavenged' components you could build it fairly quickly. You can of course substitute the blocks with alternative components. Also you can specify what frequency band to have the pre-selector tune.

If you have been following the RAE course, then some of the blocks should be familiar to you. The 'local oscillator' is a 'Hartley Oscillator'. The mixer is a 'double-balanced' mixer using diodes. Which in those days would have been germanium types. Giving a low level requirement on the 'local oscillator'.

These days with the interference levels being so high, you should consider a 'high Q' tuned antenna. To reduce the 'broadband' noise from the front end.

This is a discussion piece maybe it will trigger some construction enthusiasts. I hope so.

73 John Brock ZS6WL


 



 

2021-01-14

Baluns etc.

The club has over the years collected a lot of information. Both in the Anode magazine and on the web site.

Recently members have been putting these documents on to the WhatsApp group. This takes up space on your device and will be unreadable on the small screen. Especially for the older hams!

So for the RAE Videos:-

RAE Videos

And for the Baluns:-

Baluns etc.

 

 

73 John ZS6WL

 


2019-03-19

Yes! Finally a Geo-stationary Amateur Radio Satellite.

Just saw this on Hackaday. Es’hail-2: Hams Get Their First Geosynchronous Repeater 

Now where do I get a transmitter for 2.4GHz? Oh I know I could use the lightning modified router...

"The repeater was engineered with two main services in mind. The first is a narrowband transponder intended for phone (voice) contacts, continuous wave (CW) for Morse contacts, and some of the narrow bandwidth digital modes, like PSK-31. The other transponder is for wideband use, intended to test Digital Amateur Television (DATV). The wideband transponder can carry two simultaneous HD signals and a beacon broadcasting video content from QARS. Both transponders uplink on the portion of the 2.4-GHz reserved for hams, while downlinking on the 10.4-GHz band."
USA Amateurs need not apply...HI!
"But for hams anywhere from coastal Brazil to Thailand, the satellite is visible 24 hours a day. The equipment to use it can be a bit daunting, if the experience of this amateur radio club in Norway is any indication. They used a 3-metre dish for the 2.4-GHz uplink, along with a string of homebrew hardware and a lot of determination to pull off their one contact so far, and this from a team used to bouncing signals off the Moon." 
There is a Wikipedia page for it:-
Once upon a time a downlink on 10GHz was unheard of for radio amateurs. Now it is possible to do it at a reasonable price...

73
John Brock

2017-02-05

A Beacon on 40 metres? It is so 'last century' !

From the recent conversation on the email reflector:-

From: Leon Uys [mailto:leonuys@gmail.com]
Sent: 04 February 2017 08:49
To: 'van Rensburg Nico'; Peter Hers; Geoff Levey; 'SARL Admin'
Subject: The "Beacon" pages on the SARL web page

Good morning everyone! I have no idea who to bounce this question to, so I’m going to do a “Popcorn” move – you know, the one where you toss it in the air and hope somebody catches it. Here goes:

The web page at http://www.sarl.org.za/public/BeaconProject/Beacon1.asp is dead and it doesn’t really give a good impression because beaconing in South Africa is beginning to gain traction and I don’t want to lose that momentum.

Can I thus offer in the short term to update the page or as a minimum give a static page that points elsewhere until we get our duckies in a row?

73s
Leon Uys ZR6LU
Senior Project Manager, PMP®, Prince2® Practitioner, IBM Certified PM
leon@leonuys.co.za

---

Leon,
That page is indeed dead. It was left over from a project run some years back in conjunction with the Hermanus Magnetic Observatory, now called The South African National Space Agency Space Science facility, Hermanus. This was a major project to place standard 40 m beacons all over South Africa hosted by radio amateurs.   It was a great idea, but suffered from some personality and management problems and quietly faded away.

The page was left because of links from outside web sites over which we have no control. I have now removed the internal link.

If there is new activity and you would like to have a place on the website to post information then give me an idea of what form this would take and we can work from there.

Regards
Peter Hers
Webmaster: SARL
ZS1PHD / ZS9P

---

Thank you Peter. Understood.

Can you please put me in contact with the SANSA people so we can coordinate the fragmented information?

Maybe I’m not the right person because I have no idea how SARL works, but I’m happy to try and coordinate the beacon activity for the moment. How do you suggest we do that?

73s
Leon Uys ZR6LU

---

Hi Leon,
I found some old info on the beacon project at http://www.southgatearc.org/news/september2007/joint_beacon_project.htm.

See two attachments about the project.

As mentioned there, the technical design was done by John Williscroft ZS6EF.   His daughter Lee-Anne McKinnell ZS2LAW was the Director of the HMO. She is now ZS1LAW, and I’m not sure if she is still at SANSA.   Her info on the SARL database may be rather old, and she is no longer a member.

The design was a rather cheap device and suffered from some technical problems.   I monitored it seriously for a couple of months, but when I presented my results showing excessive time drift between the stations they got upset and stopped talking to us.

John did some other work for the SARL, but something happened, and John removed himself from the scene. Have no idea what that was about.

The main SANSA web site seems to be mostly dysfunctional, but the sub-web at https://spaceweather.sansa.org.za/ seems to be working OK.

I wonder if perhaps the best place for discussion on your new project is the SARL forum?   If you then want to provide more stable information on the SARL Web we can discuss this further. As you know the web site is rather old and facilities to update pages are rather limited.  I can easily give you a dedicated page, plus access to post information which you can do yourself.

73
Peter
---
Peter, you are a scholar and a gentleman! Thank you so much for collecting and forwarding the information.

I will have to digest all of the information before making a decision, if you don’t mind? Obviously “a page” sounds very attractive, but I don’t want to create yet another still-born project.

If I may ask a question, it would be to understand if we should be aligned with, or at a minimum be aware of, the HMO? Do they feature on our radar screen, and in what capacity?

Meanwhile I’ve started putting a few teasers in the forums, and I’ll continue to do so until we can make a better decision.

Thank you again Peter,

Leon Uys ZR6LU
---

Leon,
I have no idea if we still have a relationship with HMO – now part of SANSA.

Remember that they know more about propagation than all ZS hams put together, so it would make sense.

But I think the entire previous relationship depended on the specific people involved.

73
Peter

---
Ok, So the beacons will be 40 milliWatts and transmitting on a single frequency, within a prescribed time slot.

The presentation describes a WSPR beacon [approximately] - So how about it?
Raspberry Pi users who are radio amateurs can do this project in their sleep! The software is available already.
So the challenge is out there - Please respond to zs6wr.club@gmail.com