RADIO NOTES

Patea Mail, Volume XLIX, 3 December 1928, Page 2

RADIO NOTES

LATTE HIES DOWN.’ USE THICK LE CHARGEE. By Audiotron, A trickle charger is a device designed to maintain an A battery (accumulator) in a continual state of full charge. The charger is connected io wie A battery through a special master switch that turns on the charger by the same operation .which turns- off the switch. Since this switch turns the set on and the charger off at one operation and turns the set oil" and the charger on at another single operation the battery is being charged whenever die set is not in us«. Trickle chargers are designed to give a very low charging rate to the battery, generally nut more than one-fourth to one-half of an ampere. This charging rate is sufncient to keep the A battery hilly charged at all times and yet Is too low in amperage to harm the A battery even though the charge continues indeiinitely. Thu ,trickle chargcus unit consists of a transformer for reducing the supply line voltage, and a rectifier of either the valve type or electrolytic type. Such a unit is often milt into one housing with a specially designed accumulator of small amperehour capacity, but with an extra large space for electrolyte. Such a battery will handle an ordinary receiving set, oecause it is charged immediately after each period of discharge. The dirge electrolyte space make* it unnecessary to add distilled water more than five or six times a year. Most trickle chargers are provided with a regulating resistance, by means of which the charging rate may be varied to the requirements of the battery. This regulating resistance is usually in the form of a rheostat between the battery and the chargor. This rheostat has a resistance of about twentylive ohms, and is capable of carrying a continuous current of from one-third lo one-half ampere. Some types of trickle chargers use an ordinary incandescent lamp in the power supply duo in place of the regulating resistance in the battery line. Still other chargers provide one or more taps on tlie transformer windings, the taps being connected to a regulating switch. The master switch may also include contacts for controlling a plate voltage supply unit. At one operation this switch then turns off the set and the plate supply, which it turns on the trickle charger. The (batteries used in complete units of the trickle chargor type arc generally from thirty to fifty ampere hour capacity, although some batteries having as low as twenty ampere hours have been employed. The trickle charger requires from twenty to fifty watts from the power and light lino for its operation. Electrolytic typos use less line current than the valve typos, since the electrolytic rectifier has no valve filament to be heated. For the radio set owner who lives a distance from a charging station, the trickle charger is a very good investment. Its effect on the electric light bill will be barely noticeable, and its upkeep nil. The initial cost may seem high, but when balanced against the annual battery charging account plus the convenience of no battery carting it will bo found that the acquisition is a sound proposition. Also there is the satisfaction of knowing that your battery will always hold out during any special broadcast, such as the Tasman flight. Tell your dealer the voltage of your electric supply system and place an order for a trickle charger. This will put an end to your A battery troubles.

GENEEAL NOTES,

Eeeeptiou during the week has been fairly good for this time of the year, although -.distant stations ’have been rather weaker.

HFC ; Sydney, was receivable at phone strength at mid-day last Sunday, and the cricket scores were heard perfectly on a livc-valvo receiver. station HZF continues to bo popular aud was broadcasting some entertaining numbers on Sunday afternoon and evening.