SBM-21
Conundrum, Thu Apr 26 2018, 07:52AMHi, the tubes finally turned up.
Connected to GM counter and they seem to work, now just need to build a power supply.
Any suggestions for something relatively low powered?
(note: soldering to pin isn't a good idea but I pre-tinned the 3 ply twisted EC wire used and set soldering iron to its lowest possible temperature then heatshrunk around the wire so it can't move)
Also after some 120V zener diodes, as ebay seem to have problems when I try to order them.
-A
Re: SBM-21
AndreiRS, Fri Apr 27 2018, 09:37PM
What do you need in terms or volts and amps? AC or DC?
AndreiRS, Fri Apr 27 2018, 09:37PM
What do you need in terms or volts and amps? AC or DC?
Re: SBM-21
Sulaiman, Fri Apr 27 2018, 10:27PM
you could consider using an LM317 as a h.v. regulator
Sulaiman, Fri Apr 27 2018, 10:27PM
Conundrum wrote ...
Also after some 120V zener diodes, as ebay seem to have problems when I try to order them.
or Also after some 120V zener diodes, as ebay seem to have problems when I try to order them.
you could consider using an LM317 as a h.v. regulator
Re: SBM-21
johnf, Sat Apr 28 2018, 10:15PM
I use TVS diodes as high voltage regulators
suggest SMAJ110A from littlefuse.
they are better than zeners except for accuracy of breakdown point, but the knee is much sharper
johnf, Sat Apr 28 2018, 10:15PM
I use TVS diodes as high voltage regulators
suggest SMAJ110A from littlefuse.
they are better than zeners except for accuracy of breakdown point, but the knee is much sharper
Re: SBM-21
Blackcurrant, Sat Apr 28 2018, 10:50PM
I was thinking about building this power supply, maybe power from USB. Then use a PIC to count and display on LCD or log to computer.
Blackcurrant, Sat Apr 28 2018, 10:50PM
I was thinking about building this power supply, maybe power from USB. Then use a PIC to count and display on LCD or log to computer.
Re: SBM-21
radiotech, Wed Jun 06 2018, 10:01AM
"" Also after some 120V zener diodes, as ebay seem to have problems when I try to order them.
""
How about two neon bulbs in series?
radiotech, Wed Jun 06 2018, 10:01AM
"" Also after some 120V zener diodes, as ebay seem to have problems when I try to order them.
""
How about two neon bulbs in series?
Re: SBM-21
Conundrum, Tue Jul 10 2018, 06:57PM
Might try that, but ideally it needs to be temperature independent.
Conundrum, Tue Jul 10 2018, 06:57PM
Might try that, but ideally it needs to be temperature independent.
Re: SBM-21
Proud Mary, Tue Jul 17 2018, 08:00PM
I use a simple voltage doubler on the mains to get 600V at the few tens of microamps required.
For safety's sake, I use two miniature PCB mains transformer wired back to back (e.g. 230V to 24V, 24V to 230V) by way of mains isolation. I'm sure this is not at all efficient, but as we are only talking microamps nothing is lost by it.
I put a 68M bleeder resistor across the output of the voltage doubler, to stop it storing up nasty surprises!
Proud Mary, Tue Jul 17 2018, 08:00PM
I use a simple voltage doubler on the mains to get 600V at the few tens of microamps required.
For safety's sake, I use two miniature PCB mains transformer wired back to back (e.g. 230V to 24V, 24V to 230V) by way of mains isolation. I'm sure this is not at all efficient, but as we are only talking microamps nothing is lost by it.
I put a 68M bleeder resistor across the output of the voltage doubler, to stop it storing up nasty surprises!
Re: SBM-21
Conundrum, Fri Jul 20 2018, 08:09PM
Should work, thanks.
The tube current measurement transformers used on flat panel monitors if once side is rewound might also work.
EDIT: a low tech low power (tm) alternative might be a modified piezo transformer using a simple single transistor (12V) buzzer clamped to to the piezo cell from a gas lighter.
As I am only looking to generate relatively low voltage it would just need a feedback circuit and the slight noise should be a non issue.
Might even put this one on Hackaday!
EDIT: It *almost* works, getting the piezo out intact turned out to be more difficult especially on a used lighter.
What I really need is something which outputs a stable 130-380 volts but is only a single 8 pin SOIC, and additionally contains the measuring and I2C outputs. Surely a "single chip dosimeter" isn't impossible with Supertex having >280V output EL drivers now and the recent ones can even set their output voltage independent of frequency.
Also handy would be if the measuring circuitry inside the chip also compensated for temperature and tube aging.
And if by magic,
EDIT: Tried a new approach using HV850 but with an active rectifier modified Marx-generator like setup made from optocouplers running on Vmax 4.3V offload 53V p-p
6N135 is usable but better to use an SOIC version where possible as this is well within the ratings and its just a matter of SMD soldering.
Advantage here is that in principle it is fail-safe: one lost opto just drops output voltage by a predictable amount. so you can compensate with software if required.
It appears that the original block modules actually use a circuit very similar to the one used in gas lighters, with a unijunction transistor pulse generator driving a small transformer and 2 stage C/W multiplier.
Conundrum, Fri Jul 20 2018, 08:09PM
Should work, thanks.
The tube current measurement transformers used on flat panel monitors if once side is rewound might also work.
EDIT: a low tech low power (tm) alternative might be a modified piezo transformer using a simple single transistor (12V) buzzer clamped to to the piezo cell from a gas lighter.
As I am only looking to generate relatively low voltage it would just need a feedback circuit and the slight noise should be a non issue.
Might even put this one on Hackaday!
EDIT: It *almost* works, getting the piezo out intact turned out to be more difficult especially on a used lighter.
What I really need is something which outputs a stable 130-380 volts but is only a single 8 pin SOIC, and additionally contains the measuring and I2C outputs. Surely a "single chip dosimeter" isn't impossible with Supertex having >280V output EL drivers now and the recent ones can even set their output voltage independent of frequency.
Also handy would be if the measuring circuitry inside the chip also compensated for temperature and tube aging.
And if by magic,
EDIT: Tried a new approach using HV850 but with an active rectifier modified Marx-generator like setup made from optocouplers running on Vmax 4.3V offload 53V p-p
6N135 is usable but better to use an SOIC version where possible as this is well within the ratings and its just a matter of SMD soldering.
Advantage here is that in principle it is fail-safe: one lost opto just drops output voltage by a predictable amount. so you can compensate with software if required.
It appears that the original block modules actually use a circuit very similar to the one used in gas lighters, with a unijunction transistor pulse generator driving a small transformer and 2 stage C/W multiplier.
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