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Test run of VFD display using Arduino

Wed, 03/21/2012 - 18:43 — admin
Arduino

Among my electronics junk I found a VFD (Vacuum Fluorescent Display) display and wanted to make sure it still works and can be used in projects. It’s a 16T202DA1E display manufactured by Samsung.

16T202DA1E_hello_world

It can replace standard HD44780 based liquid crystal display out of the box. First of all it only requires 5V supply. Voltage step up circuit for lighting fluorescent display is already on board. Controller accepts same commands as any 2x16 LCD does. The pin-out of display is as follows:

OpenHardware RAM module for embedded projects

Sun, 02/26/2012 - 13:24 — admin
Microconrollers

In more complex projects where audio or video are involved, microcontrollers usually run out of internal RAM. The only solution that stands out is adding external RAM. Depending on platform and solution used there are many ways of doing this. But usually goes SRAM modules, latch register(s) and probably some other additional circuits. If you only need to add more RAM without planning all this you can use RAM module like this one made by [Wardy].

external RAM

This is simple RAM module with 512Kbytes of static RAM. It only needs 13 pins for interfacing and can accept voltage levels 3.3V or 5V. PCB layout is designed so that pins are breadboard compatible – easy to play with any microcontroller or dev board like Arduino.

Zener – one diode for many uses

Mon, 01/09/2012 - 22:20 — admin
Basic electronics

Zener diodes are specially designed diodes (heavily doped) that have low reverse voltage breakdown.

zener diode

Due to this characteristic zener diodes are connected backwards to normal operation. If zener is forward biased it acts as regular diode with forward voltage drop at 0.6V. Zener diod backward voltage breakdowns may range from 2.4V up to 100V. Truly speaking if you need like 1.2V then probably you need to connect two forward biased diodes in series for 0.6V+0.6V = 1.2V drop.

Diodes – how to choose one

Mon, 01/09/2012 - 20:33 — admin
Basic electronics

Diodes are semiconductor devices commonly used for many purposes. In generally you can imagine diode to be a valve that passes current to one direction and stops it to flow back. First thing that comes in mind – this might be a good choice for reverse voltage protection. In fact they are. But...

diode symbol

In reality things are a bit different. First of all diodes aren't perfect devices. They have so called forward voltage drop which is about 0.7V for standard diodes. So if insert diode in to power supply, say 5V the after protection you will get 4.3V where part of voltage is lost in diode. If you wanna go this way – better choose Schottky diode instead which has a smaller forward voltage drop. Forward voltage drop occurs when diode is forward biased what means current flow from anode to cathode.

Avoid smoke with power protection circuit

Fri, 01/06/2012 - 14:46 — admin
Power Supply

When designing an electronics device you want to make sure that it won't go in smoke under unexpected circumstances. You never know what may go wrong during life time of device especially if it is powered from mains. Jon Chandler made a great overview of common and pretty simple power protection circuits that may help to avoid lots of trouble. Small circuit between your battery and device may protect it from mistakes like reverse power polarity.

LTC4365

His lists starts with simple series diode which is cheap but may help protect from reverse polarity. Like any other it has a downside – voltage drop (0.7V) that may be a pain for low voltage devices.

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by Dr. Radut.