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Old 2nd Apr 2020, 12:21 pm   #1
Herald1360
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Default Another battery eliminator

Some recent posts and a little more "spare" time have prompted my getting round to one of these. A quick furkle turned up a suitable diecast box and a very handy transformer with 30V and 8.6V secondaries (I think it was originally in my 1970s Goodmans SCD110 cassette machine), the rest of the bits just happened to be in stock anyway

A voltage doubler on the 30V should give around 80V for HT and a bridge on the 8.6V won't give a 317 regulator a hard time for the 1.4V LT either.

To be continued...
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Old 2nd Apr 2020, 12:32 pm   #2
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Default Re: Another battery eliminator

The box being an 'andy 'eatsink too.
 
Old 2nd Apr 2020, 4:37 pm   #3
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Default Re: Another battery eliminator

Hmm, missed that trick. Still, I'd have to use a mounting kit whereas I can just bolt the regulator directly to the little finned heatsink which is plenty for the dissipation.
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Old 18th Apr 2020, 10:31 pm   #4
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Default Re: Another battery eliminator

Well that took a bit longer than expected but here's the result.

Not a thing of beauty but no parts were purchased (recently at any rate) to build it.

The output sockets are cunningly 3mm for LT and 4mm for HT
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Old 19th Apr 2020, 10:13 am   #5
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Default Re: Another battery eliminator

Quote:
Originally Posted by Herald1360 View Post

The output sockets are cunningly 3mm for LT and 4mm for HT
I'd have done it the other way round for 2 reasons.

The LT plugs (3mm) would fit, albeit loosely, in the HT output sockets. They would give a good enough connection to burn out the valve filaments. But 4mm plugs would not fit in 3mm sockets at all.

The HT current is a lot less than the LT current, so it makes sense to use the larger plugs for the higher current (although both sizes will trivially carry the currents involves of course, this is just me being a bit pedantic).
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Old 19th Apr 2020, 10:19 am   #6
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Default Re: Another battery eliminator

Looking good. Like me I imagine, a well stocked stores and junk box.

Just edited my post as similar comment to Tony
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Old 19th Apr 2020, 12:57 pm   #7
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Default Re: Another battery eliminator

Quote:
Originally Posted by TonyDuell View Post
The LT plugs (3mm) would fit, albeit loosely, in the HT output sockets. They would give a good enough connection to burn out the valve filaments. But 4mm plugs would not fit in 3mm sockets at all.

The HT current is a lot less than the LT current, so it makes sense to use the larger plugs for the higher current (although both sizes will trivially carry the currents involves of course, this is just me being a bit pedantic).
Good idea but given the thought of redoing the socket soldering I think I'll stick with what I've got. The other end of those leads will have croc clips on them anyway
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