In general O in diodes stands for germanium.since OA79 is a germanium diode O stands for germanium
In OA79, the letter A stands for rectifier diode and O stands for Germanium. It acts as a point contact germanium diode and also be replaced with 1N4148 depending on the circuit.
i think to make earth feel better visit my blog for more at http://www.jewelryinworld.blogspot.com OA79 represents Germanium diode. O = germanium, A= rectifier diode.
IN IN = 1N: Refers to the number of junctions (1N= 1 junction). O= Germanium, A= rectifier diode, so OA = germanium rectifier diode.
The symbol 'A' indicates that this device is made from germanium . as you may know germanium has less cut in voltage so this device is used for low power signal or for signal processing. also the leakage current or reverse saturation current of germanium is greater than silicon.
The OA79 is a germanium based diode. This conducts in the forward biased direction at ~0.3Volts. Silicon diodes Conduct in the forward biased direction at ~0.6 or 0.7 volts. If you are wanting to detect weaker signals a germanium diode is a good choice. Nowadays we have good quality low price transistors that can amplify weak signals and the difference between the diodes is not that important in many circuits. Silicon is a very common material so is cheaper than germanium Modern circuits = Good Pre-Amps = Less detection needed. Older Circuits = Pre-Amps not so good = Better detection needed. by chandan EC 3rd year
oa79 is frequency diode... it pass only the bit of frequency..
The only difference is the maximum repetitive capability which is maximum for IN4007 compared to OA79