Jump to Navigation

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.

IR remote control extender

Wed, 12/28/2011 - 17:45 — admin
Light/LED/Laser

IR remote control has a limited range and doesn't work when it is out of line of sight. But what if you need to control your appliances even if don't see them. [Michail] suggest to build an IR remote extender that stands between your remote control and device to be controlled.

IR remote extender

Nicer PC HDD activity indicator

Wed, 12/28/2011 - 17:30 — admin
Light/LED/Laser

Normally computer hard drive activity is indicated with single flashing LED when there is write or read operation performed. [Harvey Wilson] wanted something different then just flashing LED and came out with spindicator. He replaced single LED with 10 LEDs mounted in circular shape.

Pages

Subscribe to CircuitGeek RSS


Main menu 2

by Dr. Radut.