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1  Projects / ArduiNIX / Re: IN-18 Wiring on: March 26, 2014, 01:40:04 PM
I noticed on your video that the '1' char has a blue dot on it.  I've heard of this problem before.

have you tried to fix this?  have you tried actual 74141 chips?

I'd love to have some in18's but the 'blue dot' thing really turns me off.

2  Projects / ArduiNIX / Re: Adding Control Buttons To ArduiNIX? on: February 21, 2014, 10:13:43 PM
one suggestion is to use an IR receiver and integrate the ir receive arduino code (lots of examples).  once you go thru a 'learn', you can have access to a whole set of buttons and only have to have 1 hole in your chassis (for the ir) and only 1 line on the arduino needed to get you lots of buttons.

I don't know how the IR interrupt code will play with software based muxing, though.

you can use port expanders (i2c) and define them as inputs (with pullups to 5v) and to sense them you do an i2c (wire.h) read.

if there are local pins on the arduino, you can use them, too, of course.
3  Projects / Your Projects / nixie volume control display on stereo/amp on: February 12, 2014, 02:48:41 AM
one of my hobbies is DIY audio.  here is a headphone amp with a nixie volume control display!

its arduino based (uses my own arduino board called LCDuino).  this time, no lcd, but nixies.

I was going to use an arduinix board (or 2) but decided to try making my own from perf for this proto build.  I'm not muxing the nixies and so it didn't make sense to use the 'nix board (avoiding muxing was due, partly, to this being an audio system and I didn't want extra noise to come in that didn't need to be there).  here's the underside of the board:

there are 4 nixies, driven by the customary russian 74141 chips via BCD, but to supply the 16 bits needed I used 2 8-bit port expanders (i2c), pcf8574.  I use them in other projects and they were easy to apply here.  the nixies sit on a board with the 74141 and 8574 chips.  a small dc/dc converter was bought from ebay and is located in the chassis, away from the audio wiring.

there is a learning IR remote control and the volume knob is a motorized pot; if you use the IR remote to change volume, the pot moves Wink

the volume control is a relay and resistor (r2r) attenuator we call the delta-1.  it gives accurate half db steps from 0 down to -127.5db (shown on the display).

the amp tech is from AMB (called 'beta 22') and its an all discrete bipolar+fet+mosfet system.  the power supply to the amp is also fully discrete and designed by AMB.  (I designed the LCDuino and delta1).

4  Projects / ArduiNIX / Re: to multiplex or not on: February 04, 2014, 11:11:27 AM

it seems that if I choose to go non-mux, I can eliminate the driver transistors and basically just tie all anodes to +170v and simply send bcd nibble changes to each 74141 chip and latch them there until the digit/nibble changes.

I measured about 2ma of current on my nixies and so with 4 nixies on at the same time, its only 16ma of current.  I would think that the 555 circuit can drive this, but I guess I'll find out Wink

if I use the arduinix shield, the transistors are there already and I guess I would either not map them to arduino pins or map them to a single pin and make that pin pwm-able so I can dim the lights.

I've used PCF i2c port expander chips before and will likely bring one in for the extra set of 8 bits I need.

I'll post the progress as I get further.

5  Projects / ArduiNIX / Re: Blue Dot on: February 03, 2014, 03:00:01 PM
I have seen posts that talk about the russian driver chip having some problems.  it seems there are good and not so good driver chips (from what I can tell, the ground that they give is not very low and so there is not a 'strong' circuit for the tube.  not sure why the 1 numeral is the issue but I have also read about that.

do you see this blue dot when you manually connect a cathode to ground (not using chips; just literally powering the tube from the 170v supply, connecting its anode to + and the 1-cathode to gnd?
6  Projects / ArduiNIX / to multiplex or not on: February 03, 2014, 10:01:12 AM
hi, new member here.

I'm trying to decide if I have to mux the nixies or if I can run them constantly on?

what are the design trade-offs or issues to worry about?

is it a dc-dc converter power issue?  will it overheat if you drive more than 1 digit at a time?  how many can you drive, safely, at a time?

is it a lifetime issue for the tubes?

my application (one of them) will be as a display of volume level inside an audio system.  if I don't have to mux the tubes, I'd just assume not.  it will be much less activity for the arduino and less noise inside my audio chassis.

I can add extra 'pins' via port expanders and I already have 2 shields that I can use for the 4 digits that I need.  I can mount one (or both) shields on a board by themselves and then wire them to the arduino along with extra port expanders to drive the 2nd shield.  the 2nd shield could have its own dc-dc 555 circuit on it to power its pair of tubes, if one 555 is not enough.

looking for some advice on this.


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