Progress on the Replica PP4

[batterymaker1]

I do some of my best thinking while getting a haircut. So while with the family on our monthly hair sojourn, I figured I'd try my hand at a replica PP4, or 226 as they're known over here.

They're usually cylindrical with large button snaps on opposite ends, and are roughly the size of a standard C cell.

At least on this side of the pond, 226's were discontinued from the Eveready line in 2000, and most of the radios that use them barely have enough room for a standard PP3 style 9-volt.

My goal is to have a working replica that uses button cells. In theory, you should be able to remove them easily and be able to install fresh ones.

In theory.

So, first I needed to find a suitable holder.

Bottleneck #1:

Since the main container would be a cylinder, I couldn't find a proper diameter PVC pipe to do the job--either too large or too small. So I'm opting for a smaller diameter job.

The button cells I'm aiming to use are called LR44's. Inspiration hit me when looking at some of my daughter's toys--many of them use these jobbies. So, I stole a few from the toys she doesn't play with often and stacked six up.

So far, so good--they'll easily fit within the dimensions of the container.

Bottleneck #2:

While the LR44's fit within the height dimension of the container, their diameter is another story. They are smaller than the inner diameter of the pipe. So, I had to fill the gap.

Solution: Found another length of pipe that:

1--will fit snugly inside the container pipe

and

2--allow the LR44's to fit snugly inside as well.

So, here's what I'm theorizing.

The inner pipe will be the "magazine." Each end will have its respective button clip. The negative clip will held to the cradle by a wedge pin.

Installing batteries will be achieved by pushing this pin out and allowing the negative terminal to fall out of the tube.

Six LR44's will then be slid into the magazine tube, the negative terminal refitted, the wedge pin slid back into place, and then the outer pipe will be slid over this entire assembly. The outer pipe is merely fills out the body of the PP4.

For a cylindrical cover, I'll need to find some thicker cardboard and wrap around this assembly--just thick enough to give the entire battery the proper diameter. Then a cover can be placed on top.

I'm also designing octagonal covers, as the first PP4's were of this design, both American and British. I have a pic of the little transistor set that Roberts gave Queen Elizabeth, and nestled inside the carrying case were four early octagonal PP4's.

So here's what I have so far--pipe is cut, a few designs have been layed out, and I've snagged six LR44's. Now comes sweating out the working details. I aim to give you all a progress report as it rolls along.

The radio you see here is an 1956 Emerson 849--their first pocket transistor set. The 226 cover is styled after an octagonal 1959 Philco design.

Oh, and the little girl got a bob today--looks cute.

BTW--what's the diameter of a PP5? We may be looking at a two-fer in the solution for this one!

[batterymaker1]

ADDENDUM: Just checked the measurements on the PP5.

The PP4 "Magazine" I aim on building is a little shorter than the length of an PP5, also called an E177 over here.

Aside from the diameter being a SHADE larger than an original, I think the principles I'm about to apply to the PP4 can go to making a working PP5.

A "two-fer" solution indeed looks possible!

[batterymaker1]

ADDENDUM 2: Just for snicks and grins, I dummied together a version of the octagonal PP4 and glued button snaps on the top and bottom.

Added a closeup of the 3 PP4's in the Queen's Roberts Radio carrying case.

Here's what I think they looked like. This may turn out better than I planned.

[batterymaker1]

Well, that theory just went Sh*tpickle....

There just isn't quite the room to install the ends AND the cells. This might work for a PP5, which is longer, but it doesn't look good for the PP4.

I'm shutting down the shops tonight and will have a good hard think about it for tomorrow.

[batterymaker1]

Okay, I sat down and looked over a spec sheet for most of the button cells.

Looks like I have two other choices--both are narrower in thickness than the LR44's, but they still share the same diameter. So, I'll lose some battery life in return for making this work for the replica 226.

That said, the theory may have went down in flames for the 226, but I believe the same principles will work with the PP5--and even a replica E133 mercury battery, the kind used in very tiny pocket sets.

I have to wait until tomorrow to try the other button cells. Batteries Plus is closed on Sundays, and our local Walgreens didn't have enough cells on hand.

[batterymaker1]

Quick update--bought six SR43's and SR1130's--they're silver oxide versions of the alkaline LR43 and LR1130's. And they're a tad more expensive, around $2.99 apiece. However, they're cheaper than my what my local Walgreen's had them for--they were a dollar more.

Looking at the stack heights, and comparing them to the empty space left in the magazine tubes, it looks like my best choice is going to be the LR1130's--the narrowest of the group.

A pity, because the LR43 series looks to be the most popular of the group--as evidenced by Eveready offering three-packs of them along with singular packs. These LR1130's are all in singular packs.

I'll let you know what happens in a few days while I cobble up a prototype.

Bill

[paulsherwin]

It's a pity you can't use AG13/LR44s, as apart from the better capacity these are dirt cheap being used in lots of handheld games and toys. Is it possible to build a more sophisticated holder rather than just aligning all the cells in a vertical stack?

Paul

[batterymaker1]

Given the sizes of common batteries, I wish I could. It's like being caught between a rock and a hard place--good capacity but way too large, or fits about right but small.

[batterymaker1]

Unbelievable! It works!

As Edison said about the phonograph, "I was always afraid of things that worked the first time.”

I'll post pix later. In the meantime, I'm gonna run this hard and see what its lifespan may be like.

http://www.youtube.com/watch?v=DtzX3UC4wbE

[Colin]

Nicely done Bill. It looks great and I like your solution for retaining the button cells in the inner holder.

[matthewhouse]

Brilliant! The construction looks very robust, how is the card cover secured around the plastic tube? Does it unfold or does the tube slide out one of the ends when you need to refill it?

[batterymaker1]

I'll have pix in a while. Been busy with other things.

The cover is cemented together on the side and the top. The bottom is a trapdoor that is loose. Lowering it allows access to the magazine.

[Aerodyne]

Nice bob. Reminds me strongly of both my daughters when they were young... such a long time ago now, it seems. I'd have a bob haircut also but I'm told it isn't viable with only three straggly strands of hair...
The octagonal case looks very promising: 'original' and elegant. As for the cylinder thickness differential with the round variation, how about a long strip of paper rather than card, wrapped around? Might be easier to maintain circularity, possibly.
-Tony

[batterymaker1]

I've thought about that, and I'll have to see how that'll pan out.

[Mr Moose]

Hello,
Couldn't you just use three cr2032 3v lithium coin cells, they have two and a half times the capacity (210maH) of the SR/LR1130 (80maH) and as you only need three should cost less.
They are 20mm (13/16inch) diameter and the B4 is 25.4mm (1inch) which would leave you 5.4mm (7/32inch) to make a tube. Height would be no problem as they only come to 9mm (3/8inch) overall.
Yours, Richard

[David G4EBT]

Excellent stuff!

Nice to see the Dynatron Tourist in the vid - I have one in my collection. Nice radios.

Just a quick comment on the tubes: If a plastic tube with optimum inside/outside diameters can't be found, it would take only 15 mins to make one on either a metalworking or woodturning lathe from a length of solid rod such as polypenco (nylon), tufnol, or something similar.

Plastics turn well with woodturning tools and a rod which is larger than the desired outside diameter could easily be turned down to the correct diam, then the inside drilled out with a drill of the required size. If desired, a recessed rim could be turned to accept end-cheeks. The finished "tube" could then be parted off from the rod.

This might not sound very helpful if you don't have a lathe, but in the UK, USA, Canada, Oz, NZ etc, woodturning is a popular pastime and most areas will have a woodturning club nearby where several members would be happy to take on such a trivial task as a favour or a small contribution to the club funds.

(The local woodturning club of which I'm a member, has 70 active members)

Hope that's of help.

Regards,

David G4EBT

[batterymaker1]

Okay, here are pix of the assembly.

No one is more surprised than me on how easy it was to assemble, much less the fact that it worked from the get-go.

Loading the magazine is as simple as removing the paper cover, removing the outer filler pipe, pushing a pin out of the magazine, lifting an end out and installing the button cells.

I might look into the other suggestions, as they might have a hand in lowering the complexity--and potential costs.

Bill

[batterymaker1]

Easy as 1-2-3...

The bodies of the ends are plastic rod that I molded from the pipe's insides. I found it holds up better to drilling than the wood ends I was using originally.

In fact, the wooden ends would end up crumbling to bits before I was finished.

[matthewhouse]

Very neat. I'd never have thought of that ingenious design!

[Aub]

Hi,

I seem to remember PP4's being round. Was the hexagon shape a stateside thing?

Cheers

Aub