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Low Frequency B+ Generator - Keeps Killing CD4013s
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Author:  BowToEd [ 10 Nov 2018, 04:48 ]
Post subject:  Low Frequency B+ Generator - Keeps Killing CD4013s

Hello all.

Low Frequency B+ Generator V1.5: https://imgur.com/gallery/wNZclnE

The link is to the schematic for my B+ generator. I've already built it and I'm having problems. When I hook up my transformer, it kills the D flip flop used to make a 50% duty cycle.

I installed two diodes to absorb the inductive spikes from the transformer. All that did was cause an obscene amount of current to be drawn and I got nothing but current limiting. When I removed them it killed my 4013 again.

I've installed a 180 uH choke in the supply line to the ICs. The transformer has a 150 ohm resistor in series with a 100 nF capacitor across the primary. I will install another 4013 and try again but I'm looking for more tips to keep the chips safe.

This worked on an IC breadboard. I get about 175v out when lightly loaded. I also tested it today and it worked fine until I connected the transformer.

What else can I do?

Ed

Author:  gofar99 [ 10 Nov 2018, 16:55 ]
Post subject:  Re: Low Frequency B+ Generator - Keeps Killing CD4013s

Hi, A bit out of my main stream...but it appears to me that there is a ground missing from pin 1 on the 555 and next IC. If you have one there then I would figure it might work. However, I'm suspicious that the FETs are ground spiking and that would blow the MOS ICs. A rearrangement of how things are connected on the plus and negative feeds might fix it. Then too I could be all wrong. :bawling: Others might have better ideas.

Good listening
Bruce

Author:  BowToEd [ 06 Jan 2019, 20:31 ]
Post subject:  Re: Low Frequency B+ Generator - Keeps Killing CD4013s

I fixed it.

The solution was a clipper circuit in the power line to the ICs. It uses a 20v zener diode from the power line to ground and a 100 ohm resistor in series. I've also seen inverters use a large diode in the power line to the step up transformer center tap.

The output is about 145v when the current draw is 40 mA. That was a single 12ED5 stage. I'm thinking of using this to power a receiver like a Space Spanner clone. I want a good station receiver and a superhet is probably not in the cards right now.

Ed

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