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--- In NEONIXIE-L@..., Vincent DeVisser <v_f_d@...> wrote:

Most simple way seems to me to just split the nixies; half powered from one module, half from the other.

Thanks Vincent, but that is not an option, I would like to have 300V @20mA peak at my disposal for *one* Nixie tube.

I think I will have to contact the people from Traco, hmm, unless someone of you has a nice idea. :-)

Jens

Most simple way seems to me to just split the nixies; half powered from one module, half from the other.

Is there a way I can use my two MHV's parallel?

I'd suggest a call or email to their applications engineering group. They may tell you how to do it, or refer you to an app note about it.

Terry

Hello folks,

I am planning to build a "decent" 0..300V Nixie tube power supply. My
thoughts:

I have two of the MHV12300SP described here:
;
converters/mhv.pdf
They are adjustable DCDC-converters, rated 0..300V @ 10mA max.
In other words: nearly PERFECT, just the 10mA are a little low, I'd like
20mA much better. Is there a way I can use my two MHV's parallel?

Another thing: I would like to build in an adjustable resistor (poti)
150K os something like this. My first experiments show, though, that the
common potis do not work, they start smoking when changing the
resistance under voltage (a IN-14 @ 2mA wouldn't let a normal 1/4W
resistor smoke, don't worry). It is probably due to the grease-like
substance used in most potis. What kind of adjustable poti could I use?

Thanks,
Jens

--- In NEONIXIE-L@..., "threeneurons" <threeneurons@...> wrote:

Here's a drawing of my last rant:

Care to explain what that 1K resistor i circled in red, does ???

Feel free to try it out. This place seems to still have the chip:

I am temped to try it out - just a big waste of time laying out that elaborate PCB for all that chips spaced close together....

I bought two of them at my local dealer, thay were pretty expensive, but putting high tech PIC's into old gear is not correct in my opinion :-)

// Per.

--- In NEONIXIE-L@..., "threeneurons" <threeneurons@...> wrote:

I'm curious why Hans turned it into a direct drive circuit. The CA3162 already outputs its data in a multiplexed format, and the timing, from what I can get out of the datasheet, seems plenty slow enough to run nixies without any problem. If he went mux'd, he would have needed only one 74141, instead of 3. He wouldn't needed the 7475 latches, and the 7404 hex inverter. That's 6 extra chips.

Yep. I breadborded the circuit to death before going with Hans' schematic all the way. I simply could not get it to work! - I had problems with ghosting, strange noise issues and so on...

Wiring up his schematic works wonderfull, and gives me stable readout, and no flickering.

I already made the PCB's, but i am rev 1,1 now, due to some dumb mistakes. You can see the outcome here:

I just need to make a board like this for the Amp section and then a power supply.

At the moment i tried making the exact power supply with the MC34063A switcher, but i have problems with noise. I tried adding 20 uF MKT capacitance on the output of the switcher, but the LSB keeps jumping up and down 2-3 counts. For the FET i am using an IRFBC40A.

// Per.

--- In NEONIXIE-L@..., "A.J." <a.j.franzman@...> wrote:

Am I correct in thinking that this transformer with 170 V and 18 V secondaries is the one that you're using, but is not providing sufficient voltage? If so, you could wire the secondaries in series to get 188 VAC, which should give you a good 10-15 volts more DC under load after rectification and filtering.

Yep. I tried connecting the two secondaries in series to obtain a higher voltage, but found out that the 170 volt secondary just won't cut the mustard - it sags a lot under load, so i scrapped the idea of using that transformer, and i am now looking at an smps soloution instead.

// Per.

We also made our Prius into an art car. It's not solar powered.



If I were into Tesla coils, I'd bring a big one. But I'm not.

--
David Forbes, Tucson AZ

David, I'd like to see the Prius, but your link is broken.

Terry

On 28 August 2010 00:04, <michail1@...> wrote:

How would ebay item 180516094665 work out as a clock in someone's house.

Nope, No nixie, but unique.

Does this forum cater for magflip displays? I used to work up the road from
a roadsign company and I rescued several such displays, enough to make a 6
digit clock after swapping out the dead pixels (magcels?). I think that they
were made in Canada (I am in Australia). Each digit is a 5x7 matrix, about
35cm high. Magflip displays take about 8A to flip each pixel, and require a
fairly awesome power supply if you want to light up the LEDs as well. I did
make a driver with some relays but the contacts welded after a few hours. I
must try again with some big FETs.

Big industrial displays are so cool. Very few hackers seem to use them (i
only got mine by dumpster diving), I have never seen anything on the net.

Regards

TomH



--

Tom Harris <celephicus@...>


[Non-text portions of this message have been removed]

worked for me.

Funny. Didn't even turn a head, did ya?

We also made our Prius into an art car. It's not solar powered.

_

()

David, I'd like to see the Prius, but your link is broken.

Terry

Hi All,

Can anyone point me to a circuit diagram and/or a controller chip that will let me build a clock that chimes on the hour? (One chime for 1 o'clock, three chimes for 3 o'clock, etc.) I was thinking of using a solenoid to ping a piece of metal or energy chime... Thanks!

On 8/27/10 5:03 PM, threeneurons wrote:

Burning Man ! That's something I gotta go to before I keel over:

If you're dragging something technical up there (other than one of your
nixie watches), it'll probably need a diesel generator to power it.

Everything in our camp is solar powered. Of course, someone in the next camp over always parks their RV with its generator facing us.

I'm bringing SatanVision, a big LED television that I built last year from surplus red LED modules.



We also made our Prius into an art car. It's not solar powered.



If I were into Tesla coils, I'd bring a big one. But I'm not.

--
David Forbes, Tucson AZ

Yeah, I figured you were doing something tricky with those
emitter pull-downs, but I'm too busy working on the Burning Man
packing stuff to do a proper circuit analysis.

--
David Forbes, Tucson AZ

Burning Man ! That's something I gotta go to before I keel over:




One of the regular trio, to the TRW Swapmeet (tomorrow 8-28), Gary, goes there every year. He and Westdave go back a long way (hair still on the top of their heads, and none on their backs). From how Gary describes it, and from his videos and photos, its best described as a collision between Madri Gras and a maker faire, but on a heavy duty scale.

If you're dragging something technical up there (other than one of your nixie watches), it'll probably need a diesel generator to power it. Hey, wasn't there one of those on eBay, lately ?

On 8/27/10 2:15 PM, threeneurons wrote:

That's a pretty simple circuit to get the job done.

One question - what sets the 280 uA current in the MPSA42
collector to MPSA92 base connections? Shouldn't there be a big
resistor there? The MPSA42 will be saturated and the MPSA92
base is one diode drop below 180V.

--
David Forbes, Tucson AZ

I did a little 'Muntz' to rid myself of an extra resistor per stage.

David already knows this. He's been pushing around them electrons for some time now.

Yeah, I figured you were doing something tricky with those emitter pull-downs, but I'm too busy working on the Burning Man packing stuff to do a proper circuit analysis.

Thanks for the lucid description.

--
David Forbes, Tucson AZ

That's a pretty simple circuit to get the job done.

One question - what sets the 280 uA current in the MPSA42
collector to MPSA92 base connections? Shouldn't there be a big
resistor there? The MPSA42 will be saturated and the MPSA92
base is one diode drop below 180V.

--
David Forbes, Tucson AZ

I did a little 'Muntz' to rid myself of an extra resistor per stage.

As you notice all the bases, of all the MPSA42s are tied to a roughly fixed 3.4V. When one of, the 3, stages is ON, its emitter is brought to GND, but thru a 10K limiting resistor. So in reality, the one side of the resistor is at GND (0V), and the other tie to the A42s emitter, which is 0.6V (or there abouts) below that 3.4V, or ~2.8V. That's 2.8V across the 10K resistor, which translates to 280uA. That 280uA comes out of the emitter leg mostly from the collector side, and a bit thru the base (~2% with a beta of 50). The voltage from collector to emitter is almost the full 180V; Vce=180V. Power dissipation in that A42 is 280uA x 180V = 50mW. A MPSA42 can handle upto 350mW, and the MMBTA42 upto 250mW. 50mW is only a fraction of that value. We should be safe, even if those 350mW & 250mW numbers are derated, for the worst case operating temp. If that 10K resistor is ever shorted, the transistor will try to draw over 400mA (over 70W), which just might make it physically pop, if the nixie supply is up to it.

Just a tad of extra info. You can make a simple constant current device by adding a resistor to the emitter leg of a transistor, where the other end of the resistor tied to GND (0V), or some other fixed voltage (V1). The base is then tied to another fixed voltage (V2). V2 should be such that the base-emitter is forward biased. In the case of and silicon NPN, V2 should be at least 0.6V more positive than V1. The set current (flowing into the collector) will roughly be:

I=(V2-V1-0.6)/R

This is exactly what we have with the A42s of the anode drive section of the circuit above. Of course, its not perfect. That 0.6V number varies with temperature. I believe its about 23mV per degree C, if those brain cells from 30 years ago are still alive.

David already knows this. He's been pushing around them electrons for some time now. Or was he doing it before electrons formed out of the primordial soup of the big bang.

On 8/27/10 11:00 AM, threeneurons wrote:

"threeneurons"<threeneurons@...> wrote:

"per.zapro"<per.zapro@> wrote:

I have designed a PCB around Hans' Nixie multimeter design :

... The CA3162 already outputs its data in a multiplexed format,

Here's a drawing of my last rant:

That's a pretty simple circuit to get the job done.

One question - what sets the 280 uA current in the MPSA42 collector to MPSA92 base connections? Shouldn't there be a big resistor there? The MPSA42 will be saturated and the MPSA92 base is one diode drop below 180V.



--
David Forbes, Tucson AZ

"threeneurons" <threeneurons@...> wrote:

"per.zapro" <per.zapro@> wrote:

I have designed a PCB around Hans' Nixie multimeter design :

... The CA3162 already outputs its data in a multiplexed format,

Here's a drawing of my last rant:



Feel free to try it out. This place seems to still have the chip:

Fully operational, but later in the description he contradicts this by saying the sign board does not power up.

As for a home clock, I think the diesel generator might keep you awake at night.

Joe

On Fri, Aug 27, 2010 at 7:04 AM, <michail1@...> wrote:

How would ebay item 180516094665 work out as a clock in someone's house.

Nope, No nixie, but unique.

I like it! I've been needing a sign like that to warn my neighbors about
the zombie invasion.

--- In NEONIXIE-L@..., "threeneurons" <threeneurons@...> wrote:
One shows Johnivac, the only computer to use RCA's Selectron memory tubes

Nah! That's a computer with a shelf full of mouthwash bottles on top :)

And you forgot to circle the "trimming tool" on the table in left foreground. That's for the hacks.

Interesting book, that one.
Gaston