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Homemade Scope Clock DG7 tube and PIC16F876

(updated: 29. oktober 2005)


Powersupply and CRT deflection and microcontroller test circuit.
I was lucky to purcase two used but working DG7 tubes and a transformator cheap, one from Mullard and one from Phillips.
Other CRT Cathode Ray Tube types can be used, you can even rip one from an old and maybe dead oscilloscope,
then you also get the powersupply and stuff, if you are lucky the deflection amplifiers also work :-)
Then your own home made Scope Clock is soon up and running, good luck.


The test setup seen from top.


Here is the complete scope clock Powersupply schematic and PCB layout. Board with parts.
This powersupply uses an old tube gear transformator, so series resistors was used to make all the different voltages.
Voltages written on the schematic are optimal values for a DG7-32 CRT.. but other tubes can also be used, read below.
Download PSU PCB layout for easy homemade Height = 105mm, Width = 85mm.

Powersupply using special made transformator, using no series resistors:
See schematic the huge capacitors can be changed !
New Powersupply board first test of transformator
New special trafo close up picture.
Trafo in hand see the small size.


The homemade Deflection amplifiers schematic, I used in my scope clock.


This is the schematic over the blanking circuit, and PCB layout over Deflection and blanking circuit.
Baord with parts and here also
Download Deflection PCB layout for easy homemade Height = 50.8mm, Width = 111.7mm

PIC16F876 board schematic, using ZN508 DAC download and print out (updated May 2003)
PIC16F876 board schematic, using AD7302 DAC download and print out (updated Okt 2005)
See a closeup of my PIC16 demo board this board was easy to change into a scope clock controller.
I use an old ZN508 dual 8 bit parallel input DAC (see glitches), if you want a little bit better picture I suggest you use AD7302 or DAC8229 or AD5332.
If your scope tube is small or maybe a little bit out of focus, you will not notice the glitches.


Now with converter made numbers. . . SET mode is indicated really nice.
Quick time Download of running clock New Latest version has 10th of a sec indicated, looks really great.
Quick time Download of running clock Same but taken with no light in the room.



TUBE CONNECTIONS CRT TYPE DG7-32: (PREFERED TYPE)
1 Cathode -200, and Fillament 6.3V 300mA
2 Brightness Grid. (G1)
3 Connect to pin 1
4 Focus Grid (G3)
5 Not connected
6 Deflection X1
7 Deflection X2
8 Anode +300 (G2)(G4)
9 Deflection Y2
10 Deflection Y1
11 Not connected
12 Fillament 6.3v 300mA



TUBE CONNECTIONS CRT TYPE DG7-6: (usable, but voltages must be adjusted)
1 Cathode -200, and Fillament 6.3V 300mA
2 Deflection Y2
3 Deflection Y1
4 Anode +300 (A2)
5 Deflection X2
6 Deflection X1
7 Focus Grid (A1)
8 Brightness Grid. (G1)
9 Fillament 6.3v 300mA



TUBE CONNECTIONS CRT TYPE 6LO1I CCCP: (WORKS FINE, TOUCH THE SCREEN = MOVES THE PICTURE!!)
1 Cathode -200, and Fillament 6.3V 300mA
2 Connect to pin 1
3 Brightness Grid.
4 Focus Grid
5 Not connected
6 Connect to pin 3
7 Deflection Y2
8 Deflection Y1
9 Anode +300
10 Deflection X2
11 Deflection X1
12 Not connected
13 Not connected
14 Fillament 6.3v 300mA



TUBE CONNECTIONS CRT TYPE 3RP1: (WORKS FINE, Deflection Gain resistors change to 4k7)
1 Cathode -200, and Fillament 6.3V 300mA, (by the way: this tube is also sensitive to finger touch on the screen)
2 Brightness Grid.
3 Connect to pin 1
4 Focus Grid
5 Not connected
6 Deflection X2
7 Deflection X1
8 Anode +300
9 Deflection Y2
10 Deflection Y1
11 Not connected
12 Fillament 6.3v 300mA



TUBE CONNECTIONS CRT TYPE DH7/78: (WORKS SUPER FINE, Deflection Gain resistors change to 4k7)
1 Cathode -200, and Fillament 6.3V 300mA (just add a simple voltage tripler to make the +1200 V)
2 Connect to pin 1 (what can I say ?! this is the best tube so far ! focus is perfect all over the screen, and the brightness = WOW)
3 Brightness Grid (g1)
4 Focus Grid (g3)
5 (g5/a2) connect to +300 volt
6 Deflection Y1
7 Deflection Y2
8 (g4/a) Connect to pin 5
9 Deflection X2
10 Deflection X1
11 Not connected
12 (g2) Connect to new +1200 last anode voltage
13 Not connected
14 Fillament 6.3v 300mA
Tube top (g6/a3): connect to pin 12



GEC Type 408A and type E4103, 1.5" little CRT with blue screen More pictures
1 Deflection X1
2 Deflection Y1
3 Focus Grid -120
4 Cathode -200 and fillament 4V 1A
5 fillament 6 Brightness Grid, -200 min -150 max
7 Anode +300
8 Deflection Y2
9 Deflection X2

Clock Test setup




Clock in set-mode - and the Setup screen used to configure screen apperiance.
Latest version 1.00 okt 2005. with improved setup text centering, and more space,
so it is possible to use setup menu even if the screen is out of focus, or if the CRT is bad.
About the setup screen:
GO 100 = GO will save all settings and start the clock screen, 100 is the software version 1.00
50 60 = 50Hz or 60Hz mains pulse input, the selected pulse divider is underlined.
DOT = The sec dot that travels around the clock screen, underlined = ON
EDGE = The 12 hr makkers arount the clock screen, underlined = ON
SEC = The smaller numbered sec placed under the time, underlined = ON
10S = 10th of a sec fast rotating indicator placed at the top, underlined = ON
24 12 = 24hr or 12hr mode, the selected mode will be underlined
Use Switch1 and Switch2 to navigate menu, and select and exit.
Less things selected will use less CPU time, and the CPU clock can be decreased for better brightness/focus

See little video clip of this clock running: crt-clock-running 214kb


Free Download section:

1. Free download of the TGA picture to 2D cordinate converter version 0.92 with source code, made by Neil Barnes, Thanks a lot !
2. See how to make the 2D vector fonts Done the hard manual way, before the Targa converter was invented
3. All the 2D vector dots was written down.. what a waste of time..
4. PIC16 software HEX file 50Hz mains, use 16MHz xtal (+-1MHz) version beta09 date: 17. May.
5. PIC16 software HEX file 60Hz mains, use 19MHz xtal (+-1MHz) version beta09b date: 23. May.
((to get the latest version with much better looking gfx and on screen setup menu, contact Claus Urbach from nixieclocks.de))
6. Quick Time Movie of two sine waves - Same in Gif animation format

Links, more info about this subject:

1. www.sphere.bc.ca A place to get Cathode ray tubes.
2. Cathode-Ray Oscilloscope See how a CRT works.
3. www.cathodecorner.com Another type of Scope Clock, kits and complete units.
4.
5.

Made in 2003, updated 29. okt 2005. OZ2CPU