Nixie Clock Gemini Two, Assembly Instructions Manual

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Gemini Two Tube Clock 6
Update #1 (21 st May 2019)
www.nixology.uk
Component List
QTY Description
3 16 pin DIL IC Sockets
1 8 pin DIL IC Socket
1 4 Way Header Socket for Neopixel connection
1 6 Way Header Socket for BMP280 connection
1 NCH8200HV 170 V PSU – includes 4 x mounting pins
1 12V to 5V Buck Converter PSU module
4 1mm Socket Pins
2 2 x 6 Male Headers
4 Mounting pins for 12v to 5v converter (strip of 4 single header
pins)
1 74595 Shift Register IC
2 74141 or K1551 Nixie Driver IC
2 EL817 Opto Coupler IC
2 R1, R2 100R Resistor
2 R3, R4 10K Resistor
0 100nf Capacitors – optional -
4 M3 Hex Standoffs
4 M3 Screws
1 BMP 280 Temperature / Pressure Sensor
1 5V LED WS2811 / APA106 or similar
1 WeMos D1 Mini with 2 x pin headers and 2 x socket headers
Pre-Programmed
1 Two Tube Clock PCB
You will also need 2 x your choice of Nixie Tubes (not supplied). The board uses
the same 2x6 header arrangement as the PV Electronics QTC clock so any PV
Electronics QTC compatible tube cell PCB will work, just connect via a ribbon
cable with suitable connectors.
Anode Series Resistor Selection
R3 and R4 have been supplied as 10K which should provide an anode current in
the region of 3mA from the 170V supply when using a tube with a maintaining
voltage of around 140V.
You may wish to vary this value up or down depending on your selection of Nixie
Tubes. You will need to know the Anode Voltage required for your tube and the
desired current. The HV supply voltage is 170V.
Consider a ZM1210 from Telefunken, it has a maintaining voltage of 140V and
requires 2mA.
From Ohms Law (i=v/r or r=v/i), r=(170-140)/0.002 = 15K
Similarly, for a ZM1175 from Mullard, it has a maintaining voltage of 145V and
requires 2.5mA so r=(170-145)/0.0025 = 10K