Misbehaving power transformer

[dougietamson]

Rewinding with Brocotts finest...

[Diabolical Artificer]

That's excellent winding for a hand wind with a drill.

Andy.

[kalee20]

Seconded!

[dougietamson]

Originally Posted by Diabolical Artificer

That's excellent winding for a hand wind with a drill.

Andy.

Thanks, but I modified one of those low cost (£20 on sale at the time) hand winders

I cut off the original 10mm threaded bar and welded on the chuck adaptor.

I took my time with the primary wind in layers as it's a bit easier due to the 0.45mm diameter wire. A couple of 70's Genesis albums and a few breaks for tea and biscuits, a perfect way to spend a Sunday afternoon. The secondary at 0.3mm is random wound though.

For the random wind I attach an 18v drill in place of the winder handle to get a nice consistent rate.

Doug

[kalee20]

I did that too... they're really crummy-looking winders, appalling casting quality - but they do their job. (Mine, I had a local machine shop to thread the shaft to fit the chuck).

Greasing the gears and a drop of oil on the plain bearings helps a lot, but crank the handle briskly afterwards with a cloth to catch surplus flying grease!

[dougietamson]

Originally Posted by kalee20

I did that too... they're really crummy-looking winders, appalling casting quality - but they do their job. (Mine, I had a local machine shop to thread the shaft to fit the chuck).

Greasing the gears and a drop of oil on the plain bearings helps a lot, but crank the handle briskly afterwards with a cloth to catch surplus flying grease!

Another mod I did was to address inherent wobble, I drilled a 3.5mm hole in the cast iron supports for the shaft (shaft removed) threaded with 4mm tap and dropped a ballbearing in the hole after replacing the shaft, a 4mm grub screw then gives a bit of stability, tighten the grub screw to preference.

Next mod planned is to attach an old 12v NiMH drill motor and chuck (NiMH cells long dead) and use the drill handle speed control in a foot controller for hands free operation.

[dougietamson]

All rewound and reassembled now.

I added some more options.

HT is now 150v-140-130-120-110-CT-110-120-130-140-150v
Bias supply is 20v-CT-20v
2 x 6.3v @ 1.3A for filaments
10.5v @ 0.65A for DC filament supply

No load draw on primary is 110mA, bulb limiter stays dull.

Will add some load and check temps next.

Completed primary and reassembled laminations pics attached, will add bolts.