Hi everyone, this is my new nixie clock. It is my version 2.0 The first model isn't on instructables. you will see picture later. Almost the same. Difference is, no leds, some parts are in a dip package and as well board is more larger. So this is my new surface mount version. Trust me, this clock remains nobody indifferent.
-IN-14,IN-8 Nixie tubes
-High voltage psu is built-in. (up to 226v with 12v power supply). No need to buy an external one.
-High voltage digital adjustment saved in eeprom.
-Low voltage power supply can be 9v to 12v
-6 leds, digitally adjusted (push button) can be turn off. brightness saved in eeprom
-Nixie saver animation but not too often
-Little in-3 can be on,off or flashing, saved in eeprom.
-No ghosting effect.
-No exotic parts.
-Almost all discrete components. Not very expensive to do.
-Time and date as well.
-DS3231 so time is accurate and keep by battery. (+- 2ppm)
-Supported AVR are atmega 48, 88, 168 and 328
Step 1: Schematic
Click on picture, at bottom left you will see an arrow (download original) click on to have full resolution. Or download the pdf below.
Step 2: Parts List.
In the file part list.txt you will fine what you need to buy. All parts are listed. I included part number of all major components except resistor. All kind of 0805 sm resistor will do. But R32 and R33 are 1206 package 1/4w.
I bought in-8 and in-3 on ebay. I'm using used tube and so far so good. My first one is working for 2 years now without any problem.
Step 3: Gerber File
This is the file you need to send to a pcb manifacturer. You can also upload the file here to have a preview result: https://gerber-viewer.easyeda.com/
Normally you must order 5 or 10 minimum quantity. Just ask me if you whan to have only 1. I have some in my lab so maybe i could help you.
Step 4: Solder.... Before and After
You need a challenge try to solder surface mount! 0603 led are very fun :)
An advice, solder L1 only at the end. Do the programming section and if you see led7 turn on and off at the beginning you will know that all is perfect.
If all is good, install L1 and you can do the voltage adjustment.
I do not install the reset switch. This is optional. This switch can be use to replace the power cycle when we program the clock.
Step 5: Atmega Programming
Plug in your USBasp or USBtiny device in your computer and let Windows detect the device (it will report driver not found). If a window pops up asking to search for driver, just close it or click on Cancel.
At this point, download and run Zadig, it should detect the USBasp or USBtiny, or any libusb device that you have. Then in the selection box (see picture), choose libusb-win32 (v184.108.40.206), click on Install Driver, and wait for the installation to complete. Check in device manager for atmel usb device = ok. No excalmation mark anymore Download code below on this page and unzip files in a folder. I create a batch file to program the chip with .hex and fuses bits at same time. Connect USBasp or USBtiny cable in your board and you need to connect the power connector of nixie clock too.
Attention here: If you program the uC for the first time. no need to do anything. But if you are doing an update, you must enter in programming mode to disable hvps. To do so, unplug the clock, press and hold (H) and plug back in. All led will be on and led7 will be flashing. see video.
Double click on program usbxxx.bat At the end, code and fuse bit are programmed. You can use atmega 48,88,168 or 328. P or not.
Step 6: Voltage Adjustment
To enter in voltage adjustment setup. Push and hold enter button and power on the clock.
Or if you are starting the clock for the first time, the eeprom is empty and clock will enter in voltage adjustment setup by itself.
A 59khz square waveform is feeding L1. So, the coil is collapsing 59,000 times by second. This create high voltage back emf. Those spike are passing by D4 and store by C7 as low pass filter. At this point (tp1) the tension can be up to 226V with a 12v psu and 184v with a 9v psu.
The duty cycle of the waveform 59khz change the output voltage. More the duty is high more the back emf is huge resulting in a higher tension.
At the beginning voltage is very low. You will see only one or two little in-3 turned on. It's normal. By pressing on + button you will increase output voltage. Each time you press the voltage is increasing. Some number 5 will be on. This is normal, The first 3 number 5 and both in-3 are the load for the voltage adjustment.
You can monitor the output voltage with a volt meter between tp1 and gnd. I suggest to set the voltage to 160v. This one will be around 170v when clock will be running. If you like nixies brighter, go higher. Maximun duty cycle is 60% like i said, around 226v on 12v psu.
Step 7: Make a Nice Finish
Is up to you to do any kind of finish for your clock. On my side, my first clock is on a rock. And my last one is on piece of wood.
Step 8: User Manual and Conclusion
Only 3 buttons to adjust the clock.
Enter, +H, and -M
Push and hold Hours (H) or Minutes (M) and push enter. Each push increase the the clock.
Remove power, push and Hold (M) et plug back in. Push Enter to change day, (H) for month, (M) for year. Power cycle the clock. Only press enter button to pass from time to date.
Press and hold + or -
press and hold (M) and (L), press enter.
Power off, press and hold enter, power on. Click on + or - to adjust voltage. press enter when done.
Power off, press and hold (H), power on. 6 led will be on and led7 will be flashing. HVPS is off.
The engineering of this clock was very fun. And i'm very enjoying of the final product. It looking very well and it's always impressing for people who doesn't know nixie tube. I had so many good comments, if you build this clock you will have too. Now if you have any question, any bug, any suggestion. I'll be happy to ear you.