LM9022 is back

[Grahame Marsh]

Hi

Having said the LM9022 VFD filament/HV driver chip had gone unobtainium,
I've found it back in stock with RS Components in the UK at about the
same price that it was when I last bought them from Farnell. Anyone
experimenting with VFDs might find this an interesting chip. I use it
in my Approx Clock: 5V goes in and an AC for the filament and drive to a
Dickson voltage multipler comes out.

Cheers Grahame

[John Rehwinkel]

> Having said the LM9022 VFD filament/HV driver chip had gone unobtainium, I've found it back in stock with RS Components in the UK at about the same price that it was when I last bought them from Farnell. Anyone experimenting with VFDs might find this an interesting chip. I use it in my Approx Clock: 5V goes in and an AC for the filament and drive to a Dickson voltage multipler comes out.

Oh, cool! Nice catch. I'd been looking at trying to use an ICL7660 (AKA MAX1044, a switched capacitor driver) to do that job - usage I found in a polarizing supply for an electrostatic microphone. Or using a TSC428 (also available as MAX626, it's actually intended as a MOSFET gate driver, but it's basically a small dual power driver on a chip) connected to a processer pin generating PWM - a useful idea I lifted from Konstantin.

I also saw some designs for using CMOS gates to drive voltage multipliers: http://www.gyraf.dk/schematics/Voltage_multipliers_with_CMOS_gates.pdf

- John

[John Rehwinkel]

> Having said the LM9022 VFD filament/HV driver chip had gone unobtainium, I've found it back in stock with RS Components in the UK at about the same price that it was when I last bought them from Farnell.

Now they show no stock, but say they can despatch more on 26 November. I tried the US branch of RS (which is Allied Electronics), and they show no stock either, and I'd
have to fill out a contact form to even find out what the lead time is.

- John

[Grahame Marsh]

John,

I probably cleaned them out! I bought 10 and received 5 today with a
note saying the other 5 will follow at the end of the month. My brother
has a RS business account and I get them through him. Since RS are a
bit difficult with non-business accounts I will buy them for group
members or do a group order if the demand is there. Can't promise
anything as it is dependant on RS. (My bro' owes me some favours so
don't worry about him!)

Grahame

[Lucky]

Hi Grahame I too just looked a saw they were out of stock. I have a few VFD's 'hanging around' so would be interested in 5 for myself. I was going to offer the group to buy a load just to save on postage but I'm not registered atm and it would be a non-business acc anyway so would be grateful if you include me for 5 if you do a bulk order. Thanks in advance, Dave