NARRATED: 1920s Battery Charger [Restoration]

"Friction Tape" is the electrical-tape equivalent of Gaffer's Tape. As far as I can tell it is exactly the same, just more widely available in the U.S. in hardware stores than gaff. It was used not to insulate wires but as a protective coating around insulation to provide resistance to mechanical wear.

For those looking for the "black fabric tape", just search for 'Gaffers Tape', it's great stuff and widely available.

It sounds like you are calling in from Siberia on this one 😂

So, let's put the whole story of this puppy together. The ac comes in to the big coil, which is wrapped around those iron rods for the same reason that modern transformers use laminated iron frames. The iron rods carry the magnetism between the two coils. I wish you had measured the output ac voltage, but anyway, the wall ac goes into the coil which has some number of wraps and then goes back into the wall. If this is plugged in, its using power if only to heat up that primary coil. The primary coil probably has 18 or so times as many loops as the secondary wrapped around the other end of iron rods so the approximatly 110 volts in the primary gets turned into a little more than six volts out if the secondary. If you are closer to the power company, and get 120 instead, it puts out a little higher but not enough to matter to the battery. One side of the secondary gets hooked up to the ammeter, that goes on out to one clip. The other side of the secondary coil gets hooked to the carbon block, which is insulated from the frame with thoseica washers. Mica was THE standard stuff everyone used for insulating stand offs in period. You could buy packs of those rectangular washers from any electrical supply. Ok, so we have 6 volts on the carbon block... there's an air gap, and then we get the vibrating reed, and from there a wire leads out to the other clip. The reed is tuned so that its twanging frequency is 60 cycles per second (Hz) so its easy to sync up to the ac current. The reed passes through the square coil on top. That coil isnt connected to anyrhing, it has one loop around the primary coil so it's not highly coupled to the primary, but it probably runs about a volt through the heavy brass loop and the heavy copper coil. The magnetic field of that loop causes the reed to vibrate at the 60 hz of the incoming ac and make contact with the carbon block for a short time once per cycle. Thus, it turns 6 volt ac into pulsed dc. It doesnt care which is the hot and which is the neutral on the incoming ac because the fields in the square loop always make the reed make contact when the current is going the same way no matter which way you flip the plug. So, what are the small coils doing? I saw that one end is connected to the frame holding the reed, but i could not see what the other end is connected to, so i cant even guess. Does that make sense?

James Boatright

I like this. Even the audio sounds period correct.

I dig the ElectroBOOM reference...great stuff as always! Also, best blast cabinet face-plant yet.

Colin Wetz

Love the electroboom reference. So proud of our Canadian YouTubers. You, AvE, electroboom and deboss garage are my top 4.

You pronounce it sole-dering. Canadians keep the L silent because grammar

Looks like hockey tape lol

Is sodering the same as soldering or is it just my deficient Welsh hearing?

Not merely narrated.

david batig

Good....TIP! haha

Hand Tool Rescue

I actually used an antique microphone.

Hand Tool Rescue

Me too!

Hand Tool Rescue

Thanks! I try to stick to the uncommon tools.

Hand Tool Rescue

I would probably die using this in 2 seconds.

Hand Tool Rescue

I think I read that somewhere as well.

Hand Tool Rescue

I changed it to say "half-wave". Thank you!

Hand Tool Rescue

To make your soldering iron tip last much longer, I suggest you clean the tip using a wet sponge, (NEVER anything abrasive). Then coat the tip with solder, then switch the iron off. The solder will then protect the tip while not in use. I can usually triple the life of my tips using this method... Excellent vid by the way.... WELL DONE!!! 10/10

I like how you called into an AM radio station to narrate this.

You've finally perfected the retro soundtrack I hear.

Louis Ross

0:15 poor Jimmy haha

Ian Selinger

https://www.patreon.com/MrCarlsonsLab/posts

Peter Laws

Contact your fellow Canadian Mr Carlson of Mr Carlson's Lab, and he can explain it. Like you, he's another Youtuber who is too young to be this smart. :-) The coil around the core is a transformer, undoubtedly that dropped whatever house current was in that day (110 V ac?) to 6 V ac. 18:1, maybe? And then the rectifier makes the ac into dc. It's poor dc (from a, say, running sensitive electronics point of view) but fine for charging batteries. People would take their radio battery into town to get it charged periodically if they didn't have a Wincharger or the like. Contact Paul. He can explain it better and more thoroughly.

Peter Laws

I'd like to see a oscilloscope hooked to the output. I'll bet it is *really* noisy.

We used it as kids (50 years ago) on our hockey sticks (the irony!).

ChuckD

You never cease to amaze me with the breadth of devices to restore. Smashing job! The only useful thing I can add is that generally one should not operate this rectifier whilst taking a splash in the tubby. Or perhaps that is the moment one becomes rectified? Pretty neat project executed as always with a wise balance of keeping original to a safe and practical degree.

Marc McKenzie

There's a different-but-similar charger on eBay at the moment, which has a plaque on it that says "! WARNING ! Before starting rectifier, see that carbons _do not_ touch vibrator. Between charges screw in carbon brushes so that each is about the thickness of a visiting card from copper contacts." That advice probably applies to this one; hopefully you have some visiting cards handy for comparison.

Brooks Moses

Note that this is one of the reasons why early radios would have been battery-powered; you need a very clean DC source for a radio, and the only way to get that from AC line voltage using the technology of the time would have been to charge batteries with something like this and then use the charged batteries. So a charger would have been essential kit for anyone doing radio stuff back then.

Brooks Moses

I was initially thinking that too, but I'm doubtful that the capicitance would be high enough to have much effect at battery-charging-current levels. Could be, though.

Brooks Moses

As a very last note, that's going to be nowhere near a steady voltage coming out of it -- which means that you can measure the output voltage (and current) quite easily with an analog meter, but it will confuse the heck out of a digital meter.

Brooks Moses

It is, though, definitely a half-wave rectifier and not a full-wave rectifier, despite the powerful reverb at the end. :)

Brooks Moses

A key bit of the operation, which you can see at 31:45, is that the carbon block isn't "fully" engaged. It's set at a point where the metal contact is vibrating against it as the reed vibrates, so it connects and disconnects 60 times per second. (See explanations above, but it's quite clear in the video from the sparks and sound that it is indeed actually doing that.)

Brooks Moses

Also, at around 23:30, you can see that the little thick squared-off copper coil around the reed has a mounting band that goes around the main transformer. That will, I think, make that band and the main transformer windings also act as transformer, thereby inducing the current in the squared-off copper coil to wiggle the reed. If I'm remembering correctly, the induced current is inversely proportional to the number of windings, and the voltage is proportional -- which means that the squared-off copper coil will get a lot of current trying to go through it at low voltage, which is basically what you want since it's effectively a short circuit.

Brooks Moses

The thin sheets are possibly mica capacitors - they're not uncommon in radios of the time. Unlike the contemporary paper and electrolytic capacitors, which are almost always dead after so long, mica capacitors are really stable and usually still work.

Ground wires on modern electrical appliances are for safety. Modern 120V electrical outlets have three wires, a hot, neutral and a ground. The hot and neutral are current carrying conductors. The neutral conductor is bonded to ground so that if the hot wire touches ground, it will hopefully trip a breaker or blow a fuse. Older electrical systems utilized 2 wire outlets and may not have one conductor bonded to ground. The transformer feeding voltage to the home was essentially floating ( no reference to earth ground like today). Using these appliances today could be dangerous if the hot wire is connected to the case of the appliance and you touch the appliance and a grounded surface

Adding to the other bits of explanation: The giant coil is probably a 120V to 6V transformer. Where by 120V I really mean 105V or whatever the common value was at the time, and by 6V I mean something a bit higher than that so it would come out as 6V once rectified and smoothed out and such. (Given that it's a half-wave rectifier, it might need to start out at 12V since it's off half the time.)

Brooks Moses

The black cloth tape is friction tape. Search for It online. It is still readily available.

P.S. everything about this device is terrifying.

Matthew Wilson

The smaller coils might be for smoothing out the DC — coils (inductors) by themselves resist changes in current. On the other hand, putting more inductance in the circuit might make the switch want to arc more than it already does when it opens, depending on how exactly the reed timing works out. Ideally, for minimum wear, your switch opens and closes only when the current in the circuit happens to be zero (due to the AC phase versus the mechanical parts) — the same thing applies to motor commutators, or so I hear (not an expert here). Maybe the coils change the timing favorably for the switching! When it's all adjusted properly. Makes me want to poke it with an oscilloscope. Carefully.

Kevin Reid

Ok, I think that I see how this works. (Totally guessing here!) When the AC happens to be going the right way, the magnetic field around the reed pulls the reed to close the contactor. When the AC is zero or going the wrong way it's open. I'd think the output would look like a series of pulses of about the voltage of the secondary coils. This works fine for battery charging as the battery would provide more than adequate smoothing. I have no idea what the small coils are for... Inductor's to smooth the current?

Matthew Wilson

Haven't finished the video, so apologies if this was covered already, but regarding the question of the type of rectifier this is, some theory: if it has only a single set of switch contacts, then it must be a half-wave rectifier — one which works by closing the circuit when the AC is flowing one way, and opening the circuit when it flows the other way, so you get "pulsating DC" out of the switch. A full-wave rectifier, which makes use of the opposite half of the AC cycle too, requires at least two switches and usually has four — basically the same thing as a H-bridge (a.k.a. reversing switch for a motor) except synchronized to the incoming AC. (Common modern rectifiers use four diodes instead of four externally controlled switches, but there are "active rectifiers" which use control circuits driving four transistor switches, which are more efficient than diodes because diodes waste some power in their voltage drops but a transistor can be "turned on all the way".)

Kevin Reid

It's very quiet — I had to turn up the volume after the loud intro music to hear it clearly. Also sounds a bit muffled, but that's probably harder to fix. I do think it's too quiet and it would be good to upload a version with louder narration.

Kevin Reid

hmm, audio of the narration seems a bit off?

Jeremy Abel