On Friday, June 22, 2012 2:52:34 PM UTC-7, [email protected] wrote: > > I bought one of Threeneurons (mike?) dekatron spinner kits to play with > some ideas. I'm new tubes in general. Anyway, the dekatron puts out about a > 50-60 volt "pulse" at NDX. I am trying to drop that closer to 5v but at > least less than 10v. I tried using a voltage divider made of 2 resistor > going from the NDX output to ground but this stops the dekatron movement. > Can anyone offer some advice. > >
The pulse isn't 50V. Its limited by the little LED to whatever the forward drop of that LED is. ~2V (but biased 50V above ground; 50V to 52V). All the cathodes, are biased 50V above ground, and that's what you're seeing on your voltmeter. If you want to interface it to some other circuit, try using an optocoupler: http://www.allelectronics.com/make-a-store/item/4N33/OPTOISOLATOR-DARLINGTON-OUTPUT/1.html http://www.vishay.com/docs/81865/4n32.pdf Replace the current LED with the diode leg of the optocoupler. On the other side you have an electrically isolated darlington transistor (if you use the one above). Connect its collector to your low voltage logic supply. Connect the emitter to a resistor (between 2.2K and 10K), and ground the other leg of resistor. You should get a pulse off that emitter. A warning about optocouplers, they have a spec called current transfer ratio. For a regular transistor type, that could be between 20% to 50%. For darlington types is over 100%. The spinner current will only be ~300uA. If you use a regular transistor type, the output current will be only 60 to 150uA. To see 5V across a resistor, the resistor needs to be at least 82K. That's kinda high, unless you're interfacing to 4000 CMOS. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To view this discussion on the web, visit https://groups.google.com/d/msg/neonixie-l/-/MIpPLyujWhcJ. 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.
