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How to make a I guess push pull output with a lm358

be80be

Well-Known Member
I was trying to make a 1 volt output something like this
Amp1.png
With a lm358 not much luck I would use the above but not much luck with finding the chip used where i can get one fast enough.
 

ronsimpson

Well-Known Member
Most Helpful Member
1 volt output
Really one volt? How much current?
--edited--
There are a number of logic families that work with a supply of 1 volt. example: NC7SV04P5X I think with a little digging you can build it with tiny logic that runs at a supply in the 1 to 3.3 or 1 to 5.0 volt range.
NC7SV14P5X and a RC makes the oscillator.
 
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be80be

Well-Known Member
The IV-3A VFD tube from what i found Heating voltage: 0,7 … 1 V at 50 ma
I used a 1.5 volt battery which worked but I read it will mess the tube up I found this going to try it out
vfdfilamentdriver.png
 
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Nigel Goodwin

Super Moderator
Most Helpful Member
The IV-3A VFD tube from what i found Heating voltage: 0,7 … 1 V at 50 ma
I used a 1.5 volt battery which worked but I read it will mess the tube up I found this going to try it out
View attachment 121648
Well having repaired countless items using such displays, the centre-tapped transformer is pretty well what's ALWAYS used.

However, hopefully you're not wanting it to last for a long time?, as those displays seem to wear out pretty quickly - it's rare to see one that's decently visible after a few years.
 

dr pepper

Well-Known Member
Most Helpful Member
You could probably use a Lm358 circuit with outboard darlingtons as pass transistors, though you'll need fairly big heatsinks
A transformer would be betterer.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
I was trying to make a 1 volt output something like this
With a lm358 not much luck I would use the above but not much luck with finding the chip used where i can get one fast enough.
Why worry about the speed?, it's only a heater - there were usually two different options used in commercial designs (back when VFD's were used), one was similar to post #3, and was essentially a DC-AC converter 'bodged on' when it had to be powered from a single DC rail. The other, was less of an after thought, and simply used an extra tapped winding on the 50/60Hz mains transformer - so only fed the heater with 50/60Hz.

The only reason for using high frequencies was simply so the DC-AC converter could use a small cheap transformer.

As you've found, DC works fine, but isn't recommended as it reduces the already short life of the display.

BTW, the reason for the tapped windings is so you can provide the correct bias for the display on the centre tap.
 

be80be

Well-Known Member
I made a transformer last night going to try it out hopefully to night
 

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