I like the above circuit.
This is more in line with my idea of driving with OpAmp's.
This way I can apply the ideas in this sheet about offsets to zeroing the tube etc.
Edit: this pdf also drives with PWM in figure 2 ....
Trouble is the arduino's don't have enough PWM outputs.
"The striking voltage is highly dependent of temperature too..
Really ? .. why ?
Another unknown fact is that any nixie requires a tiny bit of stray radiation (light, cosmic rays, etc.) to pre-ionize the neon gas, and strike.
I have noticed that a lot of tubes won't light straight away out of the box.
Hey Spec,Hi again fire,
here is a transformerless CC display PSU which can be switched for 110V and 240V mains supplies. It is non isolated so the control signals for the tube current driver transistors would need to be isolated or the whole system referenced to the voltage rails.
For 110 V operation only, the two BJTs and eight MOSFETs would not be required.
spec
ERRATA
(1) R8 should be 4K7 not 22R
(2) For every 10 of CC display tubes (CCDTs) add another 100uF capacitor across the CCDT supply line, in parallel with C3 and C4 as appropriate.
NOTES
Hey Spec,
Was wondering about this circuit.
Why have you used 8 Mosfets ?
Can't you do it with just 2 big fat ones.
400volt P channel ones at 23watts seem to be rare ?
Just one more little clue about what this thing is going to do.
1. Tell the time.
2. Measure barrometric pressure.
3. Be a high tech disco ball.
4. Use an ST-21 Geiger muller tube .... (decatron ?)
5. Have a couple of paddles .. for restarting your heart.
Anyone think much of Rigol ? Looks ok ... I am only used to old analog ones ?
https://www.ebay.com/itm/Rigol-DS10...518700?hash=item3d0dcc9e2c:g:2m8AAOSwKtlWiuiX
Hy fire,
Because you obviously know about electronics, the circuits I have posted are only engineering outlines and have not been optimized.
The eight MOSFETs are just what I think can do the job without me having to do any thinking (I haven't even checked for suitable types of MOSFETs).
Sure, if suitable single MOSFETs can be found to dissipate 92W at 160V and withstand 400V that would work fine and would simplify the circuit. In fact, bipolar junction transistors or, more likely, IGBTs may be more suitable.
A couple of things to consider are:
(1) secondary breakdown and safe operating area (SOA) is often the limiting factor with power transistors rather than the data sheet max power rating which is a fairly meaningless parameter and is only really there for marketing purposes.
(2) The other limiting factor is maximum junction temperature: same comments as (1) above about transistor power rating.
(3) 92W is a lot to dissipate with one device and would require a huge heat sink with a low thermal resistance to air. So it would really be a trade-off between more transistors or a bigger heat sink. The more transistor approach is liable to be smaller and cheaper, but I haven't checked.
It would be possible to alter the circuit to use a single sex power transistor- NMOSFET for example.
Incidentally, the transistors would only dissipate 92W if one bank of 50 tubes were all off and the other bank of 50 tubes were all fully turned on with 12mA each.
spec
Quite a comprehensive list of functions. My advice would be to produce a universal control interface that allows you to control each tube current individually with accurately and and with high resolution. Then all the fancy stuff can be done in software.
Processing speed is liable to be critical - have you investigated the complete range of processors: Raspberry Pi and Beagle Bone Black, or even a dedicated microcontroller with a multiplexed fast digital to analog output.
You are on the right grounds but it is a bit more involved than that. With multiple devices you could run the heatsink at a higher temperature without exceeding the maximum junction temperature of typically 175 deg C which is the controlling factor.Think you are right about the heatsink ... one point source of heat coming from a fat transistor would be harder to dissipate over a large heat sink using multiple devices.
Wow .. I think that scope is a 1Mhz model I used to fix TV's in the very early 1980's not storage from memory ?Rigol stuff is nice.
My Son has a Rigol DS105- 42 for home electronics work (he is a software designer) and is very pleased with it. I had a little play with it too, when he brought it around about a year ago.
I'm old fashioned and have got a Tektronix 2235A
Universal control interface is just coming straight out of the Arduino ... (it's just what I know) .... lots of pins on the MEGA and fancy stuff must be done in software ... that's a given.
Multiplexed DAC's probably don't have idiot proof programmers .. or a great open source community and I also know multiplexing regular Nixies has it's on fair share of problems.
Processing speed of the mega is 16Mhz .... and interrupts can always be written to keep an eye on the vitals !
If it does not work with a Arduino mega . I might go down the Pi way ... though I know naff all about it.
Yup.. agreed.I know about processors etc, but have no specific knowledge of any modern micro systems like the Arduino, Pi etc. It is something I have intended to do for the last 20 years or so. One of the secrets with micro control is to do as much of the fast low level stuff in hardware and present the micro with a rationalised control inter face. In the case of the tube software all the programmer would want to see is which tube out of the 100 available and how much current say between 0mA and 12mA in 12/256 (8 bits) increments.
That way the programer would be relived of all the low level stuff and can concentrate on the artistic side of displaying various patterns on the tubes.
The other side that the programer needs to handle is the input signal which will define which out of a set of tube routines is required to execute.
There are heaps of user sites on the net for the various micro systems and there are experts on ETO too.
spec
The Tek 2235A is a 1991 model. It is a dual beam real time scope- not storage- with a bandwidth of 100MHz and a maximum sensitivity of 2mV per division. We had loads of them at work and I always wanted one. So about a year ago I bought mine from a chap on Ebay.com in the States.Wow .. I think that scope is a 1Mhz model I used to fix TV's in the very early 1980's not storage from memory ?
Would still like to have a good old fashioned analog ... I think they show the real picture.
I have been playing around with TI Webbench design.About the tube PSU.
A switch mode power supply with the following specification would be a simple design exercise for an experienced SMPS engineer, but would require more work than the mains transformer approach. Also, you would probably have to wind/modify a transformer.
(1) Input/output isolation: yes
(2) Input voltage: 100V to 250V
(3) Input voltage frequency: DC to 500Hz
(4) Output voltage 165V DC
(5) Output current 0A to 1.5A
spec
I am preaching to the wise again.Yup.. agreed.
it's called software layer abstraction !
You should look at the arduino .. it's really very easy for simple stuff.
If you know a little C++ is't a doddle.
Edit: https://www.arduino.cc/en/Main/ArduinoBoardMega2560
Check this site out ....About the tube PSU.
A switch mode power supply with the following specification would be a simple design exercise for an experienced SMPS engineer, but would require more work than the mains transformer approach. Also, you would probably have to wind/modify a transformer.
(1) Input/output isolation: yes
(2) Input voltage: 100V to 250V
(3) Input voltage frequency: DC to 500Hz
(4) Output voltage 165V DC
(5) Output current 0A to 1.5A
spec
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