Charge pump

Yup. Schmitt oscillator, three parallel buffers, voltage multiplier riding on +5. Might be a bit over 12 volts.

I could draw it if requested.

But I only have one section... :(

Feed the classic Cockcroft-Walton from the 4093

Should be ok for 1mA load. Look up old data sheets that has info on the CMOS RdSon, simulate or test

Cheers

Klaus

Requested. ...Jim Thompson

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OK, but a real CD4096 will be a little wimpy as a charge pump. Might work, might droop too much. An HC series part would be a tougher driver. HC132 or HC14, something like that.

Should I post it to sci.electronics.basics for you?

Nope. See Pg 2 and 3. Typical output current with Vdd=5V is 0.88ma high and 2.21ma low at

See "gated oscillator" on Pg 4 of the above datasheet.

However, you can buffer the output with an emitter follower and easily get the necessary current.

OOOOH SNAP

Yes, please. ...Jim Thompson

(Oops. I skipped a line on the data sheet. It should be 0.88ma both high and low. Still won't work.

A single emitter follower would need a very low value pulldown resistor. A PNP-NPN follower would work, but will cost about 1.5 volts p-p swing.

oscillator driving a 3 stage cockroft-walton?

You're running at 5V. You can't upgrade it to 74HC? That will get you the needed current capacity. Or 74AC even (beware the risetime though).

Tim

The low side of the C-W multiplier can be parked on +5, so it only needs 2 stages. The first 5 volts is free.

I'm picturing an oscillator, drivers, into cap and then, two more sections or diode's and caps... all referenced to 5V.

George H. (But sure put a scribble pic on SEB. :^)

Y'er right. I thought that the multiplier was a half wave device and only drew current on the positive cycle. That way the load acts as a pull down. However, that's wrong as it conducts on both the positive and negative parts of the cycle. Sorry(tm).

Do you agree that the 4093 will NOT be able to supply 1ma output by itself?

Probably not, if it's one section of an original CD4093. They are pretty wussy, especially with a 5 volt supply.

It would work fine with a 12 volt supply!

OK, scrawls-r-us.

There used to be a 74HC4093. Does that series still exist?