In most circuits with the EZ10A, and also the EZ10B, the current through the tube should not exceed 1.3mA when the tube is used together with cathode resistors of 6.8KOhm resistance (or 10KOhm if they are capacitively decoupled with 560pF for higher counting speeds).
With a supply voltage of 470V this results in an anode resistor of 150KOhm and with an anode voltage of 560V the anode resistor should be 220KOhm for the EZ10A. The EZ10B can usually be used with the same anode and cathode resistors but you might benefit from dividing the anode resistor into two parts, one potentiometer in series with a resistor (the resistor and potentiometer should have roughly the same value) the resistor should be decoupled to ground by 22nF for counting stability. These values results in a voltage drop of roughly 265 Volts in the tube and it will result in a voltage drop across the 6.8KOhm resistor of roughly 9 Volts, which is in accordance to the design parameters for these tubes. To drive the tube at low counting speeds you need a negative guide pulse of roughly 50V and at high speed counting you need roughly 150V negative guide pulses. If you use the tube outside of these parameters, especially at higher current it will degrade quite fast according to the articles I have read, which is the main reason for some tubes not to work that are sold on eBay. On 11 Okt, 20:58, threeneurons <[email protected]> wrote: > > Not sure what is going on but I checked the circuit and I am getting > > 613VDC with the 180K Resistor (R3) in the schematic. I increased the > > resistance to 270K and I still get 613VDC. Not sure why this is. > > Anyone have a thought on why I'm getting 613VDC? > > > John > > On what side, do you get the 613V. If its the side away from the > anode, then it may be okay. And it won't change with resistor. What's > the voltage across the dekatron (anode pin to cathode pin - any > cathode) ? What's the voltage across the anode resistor ? Divide that > number by your resistor value (used) to get the current. > > Dieter got a little carried away with the multiplier ladder. If you > use capacitors that are too small, the ripple will be outrageous, so > the average voltage won't go up to the calculated value. In the '120 > World' you really don't need more than 1.5x multiplication. REMEMBER > 120V is the RMS (Root Mean Squared - or DC equivalent work) value. The > sine wave really has a 165V peak value, and ~330Vpp (peak-to-peak) > value. Look at the following drawing: > > http://snipurl.com/1asxejhttp://cid-f9db37b8211ce831.office.live.com/self.aspx/Snippets/Multip... > > Refer to image 'D'. > > If you put 120V (110V, 115V, 117VAC) RMS into that circuit, you'll get > ~500VDC out, unloaded. The light load most dekatrons put on this > circuit (assuming an appropriate anode resistor), should not induce > too much ripple, so the voltage measured won't sage too much. On > circuit 'D', the lowest located rectifier, and capacitor form a simple > half wave rectifier & filter, which will output +165VDC, unloaded. The > left most capacitor's bottom end is riding on the input AC signal. > It's top end is tied to the anode of the rectifier, that's tapped off > the +165V. Since this voltage is dynamic (moving), the top end will > also try to stay in step with the bottom end (this is what the > coupling caps in your stereo does). But its attached to the +165V > (thru a rectifier). The bottom of the cap will make a 330V swing from > -165V to +165V. When the swing is all the way down at -165V, the top > is forced to +165V by current flowing thru the rectifier. This will > charge that cap to 330V from top to bottom. As the sine wave goes back > up, the top will still stay in step, which will make go over the 165V, > so that diagonal rectifer (now being reversed biased) is switched OFF. > When the input sinewave hits +165V, the top of the cap will be at > nearly 500V (495 or there abouts). In the meantime, it would be > charging the upper right cap. With no load, this circuit will present > a DC voltage of close to 500V. > > In the 220V (220, 230, 240) world, you can get away with circuit 'C', > which will give you 660VDC unloaded. Don't worry too much about the > voltage. > > Dekatrons, like nixies (and LEDs) are current devices. Its the current > flowing thru them that's important. And that's controlled by the anode > resistor. You can use a 'test' resistor for temporary measurements. > You need to measure (1) the actual supply voltage, and (2) the 'tube > drop' voltage from anode to a cathode. Once you have those two, then > you can determine the 'final' anode resistor value you want, from the > specs given for that tube. (ie the anode or cathode current). The > resistor will simply be supply voltage minus tube drop to give you the > anode resistor voltage. Divide that voltage (anode voltage) by the > desired current, to get the actual value, or close to it. Pick a real > value made that's less than 40% away from that calculated ideal. > > In the Philips datasheet for the Z504S dekatron, the maximum allowed > supply voltage is 1000V. That's why you see values from 400V to over > 600V commonly used. It really ain't that critical, as long as you > adjust your anode resistor, accordingly. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
