NE555 turns 50

Rampz

Well-known member
It was the use of the 555 that made me search out the 08m2 for my projects that you all have been subjected to recently, I have used a few hundred in the 18 months before PICaxe found me, not look back.
 

erco

Senior Member
Analog, digital, I like 'em all. The mere fact that you can get 50 pcs of 555 DIP timers delivered for under $6 is reason enough to stock up/hoard IMHO. Even less for SMT! https://www.ebay.com/itm/223338688488

They can put out 200 mA, that can save a driver transistor or two. Awesome potential, I still use them at every opportunity... several times a year.

 

erco

Senior Member
I was in my early teens when I first learned of the 555 timer. The (paper!) magazine Popular Electronics featured a 555 metronome circuit in one issue. Many hobbyists who wrote letters published in PE were anti-IC... they thought they were a bad shortcut and you were cheating if you used them. Discrete parts RULED then!

Below from https://www.electronicdesign.com/archive/article/21752153/whatever-happened-to-the-electronics-hobbyist

The number one reason why the electronic hobbyist has declined in number is...the integrated circuit.
 

PhilHornby

Senior Member
Back in the 1980's, the state-run G.P.O. gave way to British Telecom and the promise that soon we'd be able to buy phones and accessories, that simply plugged into a wall socket...

I took this as a green-light for building my own telephone accessories and designed a bell replacement, using a 555 timer. The first version was quite simple - just to prove the concept (though it did nothing of the sort!)

The 555 timer can easily run a loudspeaker at high volume, so I took the basic astable circuit and added a bit of my own magic to Pin 4. Feeding the incoming phone line through a full-wave rectifier and a zener diode, seemed to me to be a great way to detect the "Ring" signal.

What it actually did - and to this day, I don't quite understand how - was receive my local BBC Radio station (medium wave AM). I'd somehow built a single IC, loudspeaker radio o_O

I don't think even Sir Clive Sinclair managed one of those :)

(A little knowledge is a dangerous thing!)
 

erco

Senior Member
What it actually did - and to this day, I don't quite understand how - was receive my local BBC Radio station (medium wave AM). I'd somehow built a single IC, loudspeaker radio o_O
I live just a few miles from KNX-1070, a 50 kW AM radio station in Los Angeles. It's hard to NOT pick up a news broadcast on anything with an audio amp & speaker, which rectifies and detects any suitable signal. Our church is less than a mile away. I teach robotics classes there occasionally to kids, and I have started collecting parts for my next class, making a crystal radio. I'm sure a short antenna is all that will be required, just a few feet of wire, or maybe a SPOON. :)
 

papaof2

Senior Member
ah yes ... I remember seeing suggestions that a connection to the metal finger stop on a dial telephone, made a good short-wave aerial.
Potentailly capacitively coupled to a hundreds of feet/meters of aerial telephone wiring would provide a large capture surface for radio waves of all types ;-)
 

erco

Senior Member
ah yes ... I remember seeing suggestions that a connection to the metal finger stop on a dial telephone, made a good short-wave aerial.
Good news: It's true, that's a great antenna.
Bad news: When's the last time you saw a rotary phone connected to metal wire phone line? Fiber optics rule the waves these days.
 

papaof2

Senior Member
I have never played with valves but a great video of someone making a 555 with them really great thanks for sharing it.
What? You missed all the fun of drilling a steel chassis so you could use the hole punches for the different size tube sockets? We all sympathize with your deprived childhood ;-)
 

erco

Senior Member
NOTHING will ever beat the lovely warm glow of an old vacuum tube radio with incandescent bulbs illuminating the slide rule dial. The heat and resulting smell of warm braided-insulation wiring & hot dust are... intoxicating! I still have my 60's-vintage Heathkit ham radio shack and several AM/shortwave radios, including a giant wooden 1941 Philco radio/phono console, all which use tubes.

I'm lucky to live in Los Angeles with decent access to vacuum tubes (and testers). There is a nearby monthly electronic swap meet with new and vintage parts & items, and several marvelous old electronics stores with new and old parts, and a tube room & tester!

41-605.jpgEp1-Heathkit.png
 
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erco

Senior Member
Just looked at the Torrance web page. Wish it wasn't 2200 miles away :-(

Just 2 miles for me! I know, I'm very lucky. This was another great old-school store just 1/4 mile from me which sadly closed in 2016, along with my beloved Radio Shacks.

 
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papaof2

Senior Member
I made out like a bandit on some things of use when the Radio Shack stores in the area started to close - if you were there early enough in the clearance... Along the way, they also had some BOGO parts deals at radioshack.com and I collected a lot of 10 gauge red and black automotive wire - great stuff for small solar systems ;-)

When Lafayette Radio (anyone else remember them?) was in business, I worked at one of their affiliate stores in Tennessee - LONG in the distant past... Does that give me some type of "elder geek" status? ;-) I still have one of the Lafayette "Solid State" CB radios (still working and it was "High Tech" compared to all the tube CBs of the day) and a VOM from Olson Electronics (needs a battery terminal replaced for the Ohms ranges) - welcome to the Old Electronics Museum ;-) If you'd so kind as to help the curator from his chair, he'll point you to the other displays...
 

tmfkam

Senior Member
We still have John Birkett's in Lincoln. A genuine treasure trove. Some walls were lined floor to ceiling with valves (tubes?). I once asked to an obscure valve with a low voltage heater for a portable radio. "I've not got one here, but I've got one. Come back in a few days." I went back and not only had he got the valve (new old stock) but he remembered me, and could tell me what the valve was and what it was used for (IF amp, oscillator and mixer).

Opened in 1960 and still open a few hours a week. John has to be 80+ years old so perhaps we should be respectful and grateful that he opens at all.birkett1.jpg
 

Rampz

Well-known member
We still have John Birkett's in Lincoln. A genuine treasure trove. Some walls were lined floor to ceiling with valves (tubes?). I once asked to an obscure valve with a low voltage heater for a portable radio. "I've not got one here, but I've got one. Come back in a few days." I went back and not only had he got the valve (new old stock) but he remembered me, and could tell me what the valve was and what it was used for (IF amp, oscillator and mixer).

Opened in 1960 and still open a few hours a week. John has to be 80+ years old so perhaps we should be respectful and grateful that he opens at all.View attachment 25177
Yep great place i have been a few times over the years, didn't know he was still open, i bought a 20A variac from there had to walk across lincoln carring 20kg of variac :)
 

papaof2

Senior Member
We had a place called Halted Solutions in San Jose. It had been there so long that Steve Jobs bought surplus parts to make one of the early Apple prototypes! Flip through the photos on Yelp - it was an amazing place:
I bought from HSC online - even found the solid state "guts" of a 400 watt, 12VDC to 120VAC inverter (in the original factory packaging) for a few dollars. The design of the original inverter package was such that you coiuld add a second inverter board and make the 400 watt inverter into a 750 watt inverter. All modified sine wave but the price was right ;-)
On the other hand, I've been looking for ways to turn DC into AC since I was in high school (Yes, we had moved from candles to oil lamps at that point ;-) I have two pieces that are now collector's items: mechanical vibrator driven, square wave via a transformer, 12VDC to 120VAC inverters, both made by CDE. One 80 watts, the other 140 watts; the bigger one complete with a three position switch that controlled output voltage and charge current from the built-in AC operated charger - and the metal case had space for a 12 volt lead acid battery of a common size (common in 1957). Those are in the basement of the Old Electronics Museum ;-)
 
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