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This is a design of a clock based on popular lamp VFD IW-18. The name PipeBOMB is due to the fact that the clock looks like a bomb. It also is equipped with a function of counting down to a pseudo explosion (CountDown counter). The lamp is controlled by drivers Maxim MAX6920.
Atmega32 powered by crystal quartz 11.05920MHz
The clock consists of a few cooperating modules:
- main board of the clock
- DC/DC adjustable voltage converter module, based on MC34063
- RTC clock module with a battery DS1337S+
- BlueTooth module – BTM-222
*] LED module
Some information about the IW-18 supply:
- glow voltage from 3V to 5V (5V can be decreased by means of 2 LEDs 1N4148)
- voltage for anodes:
- at static display max: 20-30V
- at multiplexed display: 50-60V
- power consumption: max 120mA
In order to apply multiplexed displaying, you have to increase the voltage. To do that, you can use the chip MC34063. Schematic below. The converter is a separate module, so that it can be used for different purposes. Input voltage of the converter can be from +5V to +12V. Output voltage can be adjusted in the range of +15V to +50V. Current efficiency is enough for that.
As you can see, clock used in this design is RTC from DALLAS DS1337S+. Unfortunately, it requires 3,3V (theoretically) while the circuit is powered by +5V. If you do not want to create an additional stabilizer, you have to decrease the supply of the chip by means of two diodes 1N4148 to approximately 4,1V.
If you want to add synchronization of time with server/time models SNTP on the Internet, you have to provide communication with the PC. This communication can be completely wireless when you use BlueTooth – module BTM-222.
More information on such modules:LINK.
It was placed in plexiglass, because metal housing would interfere the transmission. You can also put an antenna outside and do not use plexiglass, although it is better to hide the antenna under the module in the plexiglass which additionally disperse the LED light.
LEDs were mounted on a module of such diodes and powered from the chip ULN2803. Two such chips and modules are designed to be on the main board, but in this project there is only one on the left.
Functions of the clock:
- full support of IR remote control – no buttons
- alarm with melodies – speaker
- automatic dimming/brightening both VFD and LEDs, using the photoresistor connected to one of ADC inputs
- automatic saver of VFD lamp/after pressing any button on the remote control – it brightens
- communication from the PC via BlueTooth
- time synchronization via the Internet – SNTP and own software
- clock/alarm/melody settings – everything can be done from the PC or remote control
- possibility of work in vertical position
- built-in BootLoader for exchange of BIOS of the clock without disassembling the housing and connecting cables – everything wireless by means of BlueTooth - more information: LINK
The whole is powered from stabilized power supplt +12V of efficiency 1,25A. All LEDs are powered from the 12V and resistors are selected accordingly to the voltage.
The program was written in C.
Lamp in the darkness without the filter:
And with the filter:
Connection with BlueTooth module in windows terminal:
Socket in the back of the housing:
Link to original thread (useful attachment) - PipeBOMB - zegar VFD,lampa IW18,Pilot, BlueTooth, sync. SNTP