Germanium Diodes
Germanium Diodes
Learn about the advantages of Germanium Diodes
electronics
Diodes are a very important component of most
alternative energy generating systems - for example in
PV solar panels they are used to stop energy being radiated back out into the night sky from the
battery bank, and in
wind turbine generators they are used to
rectify AC into DC electricity.
Most
diodes are made of
silicon because of its ease of processing and stability, however they have one disadvantage: a
silicon diode has a forward
voltage drop of around
0.7 volts. This means that if you had a 7.0 Volt rated solar panel charging a battery via a silicon diode, only 7 - 0.7 = 6.3 Volts would be seen by the battery - the remainder is
lost as heat in the diode.
In a
Bridge Rectifier the current passes through
two diodes. Therefore the total
forward voltage drop is a whopping
1.4 volts - a significant amount in
low voltage systems.
Germanium Diodes
A
Germanium Diode (such as the
1N34 pictured above) will typically have a forward voltage drop of just
0.3 volts which means they are
much more efficient. Older germanium diodes had a larger leakage of current at a reverse voltage, but now
American Microsemiconductor and others supply a range of improved
low current leakage germanium diodes. Diodes such as the most common 1N34A can cost as little as 5 pence each.
Buy Germanium Diodes
It is not always easy to find
germanium diodes as they are not a very popular item. One of the best ways to obtain them is to purchase
vintage stock made available for sale on
eBay.
At the time of updating this article (August 2008) there were OA47, OA81, OA90, OA91, OAZ210, IS689, 1N34A, 1N42, 1N60, AAZ17, and AA119 germanium diodes all listed for sale - some new and some vintage / used.
Click here to search
eBay UK for
germanium diode, or here to search
eBay USA for
germanium diode.
In the UK
Rapid Electronics often have one or two
germanium diodes - click to view their latest listings.
More Information about Germanium Diodes
While
silicon diodes are resistant to the heat from soldering,
germanium diodes can very easilty be damaged. Therefore a crocodile clip or other suitable
heat sink should be clipped onto the lead between the diode body and the joint to be soldered.
An interesting article about the practical use of
Germanium Diodes in a crystal radio set is here, and discusses the forward
voltage drop of a selection of germanium diodes in real world testing. The
OA47 came out tops with a forward voltage drop of under
250mV.
Article Last Modified: 13:43, 8th Aug 2008
Recommended Related Articles
People who read this article also enjoyed the following articles:
Solar Battery ChargingMake a solar charger for NiCd and NiMH rechargeable AA, AAA etc batteries
Article Last Modified: 09:43, 30th Jul 2007solar | educationSolar Battery Charger With LM317TFind out how to make a current controlled solar battery charger using an LM317T
Article Last Modified: 09:34, 30th Mar 2007solar | education | electric circuitLED Dimmer CircuitFind out how to put together a simple but efficient PWM dimmer circuit for LEDs
Article Last Modified: 16:03, 21st Nov 2007lighting | electronics | electric circuitMaking Very Accurate TimersFind out about how to make very accurate electronic timers
Article Last Modified: 14:12, 20th Feb 2008electronicsVoltage Doubler for Solar Battery ChargerBoost the voltage of a solar panel to power higher voltage devices or charge batteries
Article Last Modified: 13:15, 16th May 2007solar | electronics | education40 Amp Blocking Diode 1N1190AFind out how to use a blocking diode with a wind turbine generator
Article Last Modified: 13:36, 20th Aug 2008wind | electric circuit | solarLM317T Voltage Regulator ChipLearn about the LM317T and its uses in renewable energy projects
Article Last Modified: 09:34, 30th Mar 2007electronics | electric circuitBasic 4 AA Solar Battery Charger PlansMake a simple solar charger for 4 AA rechargeable batteries
Article Last Modified: 09:43, 30th Jul 2007solar | educationLM741 OpAmp Voltage IndicatorPlans for a simple voltage high/low indicator built around an LM741 operational amplifier
Article Last Modified: 09:31, 8th Oct 2007electronics | electric circuit | generalElectricity with Stepper MotorsFind out the basics of generating electricity with stepper motors
Article Last Modified: 17:07, 10th Jun 2008wind