Faulty Fixed Condensers

Radio Record, Volume III, Issue 16, 1 November 1929, Page 30

Faulty Fixed Condensers

An Efficient Test COMPONENT‘ which is usually taken on trust by the constructor, but which should ‘be beyon reproach in design and construction, is the large capacity fixed condenser placed across the "B" battery. The least leakage through the dielectric material or via the containing case of such condensers will place a continuous drain on the "B" battery, and will prevent the condenser from fulfilling its proper function. The ordinar: fixed condenser test which makes use of a single dry cell and a pair of headphones is not com‘plete enough with the larger capacities. A much surer test can be carried out with a pair of wander -lugs and a "B" battery. Attach the leads of the wander plugs to the terminals of the condenser put one of the plugs in the negative socket of the battery and brush the other one lightly across the positive socket. Not less than 50 volts should be used. There should be only a small, sharp spark, as the condenser ch: rges up. If the insulation is hopelessly faulty, there will be a big. spitting spark as the plug touches the socket. To complete the test, after brushing the plug on the positive socket bring it into contact with the »>ther plug, when there should be another small spark as the condenser discharges again. Now touch the plug on the positive socket again, and then place it on a piece of ebonite. If, in a few minutes’ time, a small spark can still be obtained on bringing the two wander plugs together, the condenser is in perfect order.