Bench Soldering Equipment / Tools Suggestions

[zdjh22]

I was working on a transformerless power amp design once before polarized plugs and got it backwards. Made a mess of a ground trace in a pretty expensive meter, alas.

As a naïve 1st-year grad student in physics (summer before my 1st year actually) I was interfacing via an add-in digital I/O board my Apple ][ computer to the department's brand new expensive SQUID magnetometer, which had a nice digital I/O interface. I happily connected pins, including the digital grounds, turned on both machines, and sadly watched as the smoke poured out of the magnetometer. I was convinced I was doomed to be kicked out, before learning the lesson that in grad school "teachable moments" are celebrated (which is awesome, as long as you survive). I became fast friends with the electronics shop, who taught me the wonders of optoisolators; from then on I helped them with computers and they helped me with electronics.

May the pain associated with your teachable moments be limited to blown fuses, popped breakers, and the occasional burned or lifted trace. My EE father taught me well - one hand behind your back before touching anything with the other hand.

 

[gene_stl]

I had a variac that had an isolation winding built into it. It had a current meter and a non ventilated case. Unfortunately it got away from me. Made in USA. I think it was a Staco. PN series if I remember correctly.

https://variac.com/staco/PDFCutSheets/VT isolated.pdf

 

[MidiMagic]

One of my favorite pieces of lab bench equipment is the current-limiting DC current source, which allows setting both the output voltage and current limit. A very safe way to do DC testing, and it gives one both a constant voltage and a constant current source in one box.

Sadly any analogous AC power source on the market is very expensive. This dim bulb tester is brilliant (pardon the pun). The variable resistance (R increasing with temperature) of the incandescent bulb serves the same purpose as the current limiter in a current-limiting DC supply.

I was sure Feynman talked about this, but I looked it up and he just tells a story (in “Surely You’re Joking Mr Feynman”) about using a set of 3 bulbs as a child and investigating series and parallel resistance. He noted that his equations didn’t work out because he didn’t recognize the variable resistance with temperature.

I did a study on this last year. I found that the resistance of the bulb is usually 8 to 10 times when lit as it is when it is cold. The resistance change is linear to the voltage on the bulb.

I have even used this effect to make a passive matrix decoder that reduces back separation when strong front center content is present.,

 

[bsco]

you have to be very careful when working on some of this equipment....

 

[barfle]

As a naïve 1st-year grad student in physics (summer before my 1st year actually) I was interfacing via an add-in digital I/O board my Apple ][ computer to the department's brand new expensive SQUID magnetometer, which had a nice digital I/O interface. I happily connected pins, including the digital grounds, turned on both machines, and sadly watched as the smoke poured out of the magnetometer. I was convinced I was doomed to be kicked out, before learning the lesson that in grad school "teachable moments" are celebrated (which is awesome, as long as you survive). I became fast friends with the electronics shop, who taught me the wonders of optoisolators; from then on I helped them with computers and they helped me with electronics.

May the pain associated with your teachable moments be limited to blown fuses, popped breakers, and the occasional burned or lifted trace. My EE father taught me well - one hand behind your back before touching anything with the other hand.

IIRC (it was 50 years ago, after all), the input was opto isolated and there was a big capacitor on the output but yes, trouble-shooting that device was fraught with peril. I also smoked a speaker with that amp’s big DC offset (it might have been the same test, but, well, it was 50 years ago).

 

[Michaelteg24]

Hey, being a daredevil and Old School kind of guy I say just plug it in and right before you turn it on yell out " FIRE IN THE HOLE!"

But in all seriousness, and using my better sense, it is best to use an isolation transformer with a high enough Volt-Amperes rating along with a Variac!

I have used them along with "good sense practice" for many years!
In fact I think that they are two items that are a must have for anyone who wants to work on electric/electronic equipment!

Using Incandescent light bulbs is a good idea for when you want to have, or allow, a large inrush of current; but want to put a time limit on how long the higher current is allowed to flow!
All that being said I have put my two cents worth in on some of the comments and conversations recently posted!
This is a good forum to have joined! Very interesting subjects and ideas you all have!

 

[Michaelteg24]

One more thing! The TV sets in the old days didn't use a transformer in the power supply so as to keep the price down for making them!
This resulted in what was called a "hot chassis!"
When you touched the metal chassis and a good ground you found out why it was called that!
You quickly learned why an isolation transformer was a must have item in the shop!

 

[barfle]

One more thing! The TV sets in the old days didn't use a transformer in the power supply so as to keep the price down for making them!
This resulted in what was called a "hot chassis!"
When you touched the metal chassis and a good ground you found out why it was called that!
You quickly learned why an isolation transformer was a must have item in the shop!

It all depended on which way you put the non-polarized plug in. That tranformerless amp I descibed earlier was definitely a hot-chassis design. I don’t believe it made it out of the lab, but that was normal for Altec in those days, not releasing new products.

 

[par4ken]

It all depended on which way you put the non-polarized plug in. That tranformerless amp I descibed earlier was definitely a hot-chassis design. I don’t believe it made it out of the lab, but that was normal for Altec in those days, not releasing new products.

TV's and also the "American Five" tube radio design (which was almost universal) had a hot chassis. The tube filaments were connected in series, designed so that each tube in the line received the correct filament voltage. They could have been made more safe back then if polarized plugs would have been used. I shocked myself many times while tweaking the slugs of an old radio while standing on the concrete basement floor attempting to better pull in those week AM stations!

Equipment from the seventies, maybe even into the eighties lack the polarised plug. It can be a bit frustrating when you can't plug a modern piece of equipment into a vintage accessory connector. That is why I have to use such a large power bar!

 

[Michaelteg24]

It all depended on which way you put the non-polarized plug in. That tranformerless amp I descibed earlier was definitely a hot-chassis design. I don’t believe it made it out of the lab, but that was normal for Altec in those days, not releasing new products.

Yeah that's true! That brings back many memories!
It made it a 50/50 chance of electrocuting yourself when using the "cheater-cord" to power it up with the back cover off of it.
That's why I started using isolation transformers soon after I nearly killed myself several times!
The TVs, radios, phonographs and other things had a sort of "so called safety interlocking system" wherein the end of the power cord that made the connection to the set could only be made with the proper polarity when you put the back cover back on it!
(Amazing how in the English language we use the same spelling for two different things! No wonder people who are learning the English language say that it is very confusing)
There was a clip that held the end of the cord onto the back cover. Once the back cover was off that's were the cheater cord came into popular use!
No one wanted to pull the clip off and remove the power cord from the back cover! We always had a good supply of cheater cords handy!
I still have several cheater cords up in the lab from the old days! Imagine that! 50 to 60 year old cheater cords still around and available!
If memory serves me correctly I always hated having to align the back cover with the attached cord so that I could get it into the socket on the set!
Because if you didn't get it fixed yet you had to go through the whole thing over again!

 

[Michaelteg24]

I did a study on this last year. I found that the resistance of the bulb is usually 8 to 10 times when lit as it is when it is cold. The resistance change is linear to the voltage on the bulb.

I have even used this effect to make a passive matrix decoder that reduces back separation when strong front center content is present.,

Interesting! Very interesting! Spoken with a German accent!
Perhaps the linear relationship is why Hewlett and Packard used a light bulb in their famous signal generator!
A 100 watt light bulb was often used as a dummy antenna for trouble shooting 75 watt transmitters used in the novice bands back in the day too!

 

[bsco]

Bottom line..use an isolation transformer and some form of current limiting.....and keep one hand in your pocket when doing live measurements....

 

[Michaelteg24]

As a naïve 1st-year grad student in physics (summer before my 1st year actually) I was interfacing via an add-in digital I/O board my Apple ][ computer to the department's brand new expensive SQUID magnetometer, which had a nice digital I/O interface. I happily connected pins, including the digital grounds, turned on both machines, and sadly watched as the smoke poured out of the magnetometer. I was convinced I was doomed to be kicked out, before learning the lesson that in grad school "teachable moments" are celebrated (which is awesome, as long as you survive). I became fast friends with the electronics shop, who taught me the wonders of optoisolators; from then on I helped them with computers and they helped me with electronics.

May the pain associated with your teachable moments be limited to blown fuses, popped breakers, and the occasional burned or lifted trace. My EE father taught me well - one hand behind your back before touching anything with the other hand.

I worked at CPI in Palo Alto CA and if you pointed your finger at a high voltage power supply they would have to fire you for safety reasons! The potentials developed in some of the supplies could cause a lightning bolt to reach out and touch you in a most unpleasant way! They didn't want you to be a victim of your own stupidity!
In one very large building they have a Westinghouse transformer that itself is the size of a large building that produces millions of volts and the rectifiers and capacitor banks are all specifically arranged to prevent arcing between the components. These too are gargantuan components.
The point being that when powered up no body could be in that building or they would become a lightning rod and be found as a pile of carbon on the floor!
So...no pointing out things in the work place!

 

[zdjh22]

Here is the Cockcroft-Walton generator where I used to work (Fermilab). This is the first stage of the particle accelerator complex there. It provided 750,000 volts to accelerate H- ions. From here they were stripped to H+ (bare protons), sent through a series of LINAC cavities (linear accelerator) and then into two consecutive synchrotron rings. Center-of-mass collision energies between protons and anti-protons at the final ring were about 10^12 electron volts (the protons and anti-protons circulated in opposite directions). The final ring is roughly 3 miles in circumference, with a liquid helium delivery system for all of the superconducting magnets.

Some complexes use van de Graf first stage accelerators instead, up to about 1 million volts IIRC.

On this Cockcroft-Walton every corner is rounded so that the electric field strengths are less than air ionization potentials - so no lightning bolts. For scale, a human standing next to the left tower would come up to slightly above the second donuts.

 

[Michaelteg24]

Here is the Cockcroft-Walton generator where I used to work (Fermilab). This is the first stage of the particle accelerator complex there. It provided 750,000 volts to accelerate H- ions. From here they were stripped to H+ (bare protons), sent through a series of LINAC cavities (linear accelerator) and then into two consecutive synchrotron rings. Center-of-mass collision energies between protons and anti-protons at the final ring were about 10^12 electron volts (the protons and anti-protons circulated in opposite directions). The final ring is roughly 3 miles in circumference, with a liquid helium delivery system for all of the superconducting magnets.

Some complexes use van de Graf first stage accelerators instead, up to about 1 million volts IIRC.

On this Cockcroft-Walton every corner is rounded so that the electric field strengths are less than air ionization potentials - so no lightning bolts. For scale, a human standing next to the left tower would come up to slightly above the second donuts.

View attachment 103615

Beautiful ! An amazing thing to behold!