| Show edited by 0 douglas editor of radio PH see is see 07 diagram showing directions which must be followed for construction ot of the two stage cry crystal stal amplifier by PETER MOMBELLO tube amplification with its persisting noises tins lies been tile the only thing to prevent a radio set from comparing c om parIng very favorably with a phonograph for cleo clear r music also because of these noises ninny many radio fans who are satis sails fled find with the locals have gone back to the crystal sets to enjoy clear natural and faithful reproduction T these hese properties of the crystal account for its existence in tills this ago age of sets if the crystal can be used its as a detector why cannot it be used as an amplifier if this term Is appropriate As 8 a matter of a tact fact it it can be used in tho the latter way and tile the rest of this article artic e will he be devoted to t the he construction of 0 f a two stage emp lifler using crystals the following parts will be needed two audio frequency transformers one of 10 to I 1 ratio find and another of 0 to 1 ratio two perfectly insulated crystal detector units two very sensitive galena crystals two mica fixed condensers mad capacity one B battery volts six binding posts and one badlon panel aby 7 by 5 MI all these parts fire are to be very efficient and considering cons aldering the fact that they can lie be used over and over again it Is worth wh while e to spend a little more and get good ones tile the first time I 1 must follow directions the diagram given with this article must he be followed very carefully or of special importance Is tile the connection after the first amplifying crystal the wire that comes from the secondary of the first transformer and goes through the crystal Is to be connected to the secondary of the second transformer if this connection should go to the primary the amplifier would not work and the sensitivity of the first crystal would be ruined by the battery 20 no baseboard Is to be used the transformers should be mounted at right angles to each other on the inside of the panel the first crystal should be placed above the first transformer and the second crystal above the second transformer on the front of the panel the connections to both of them should be reversed to give the best volume the input posts should be on the left and the battery posts and output posts should be on the right in wiring use pure soft drawn copper capper wire or gold plated wire under no circumstances should you use the tinned bus bar wire as its surface con ductility Is very low make blake a all 11 connections direct in straight lines ano and solder absolutely every connection wien soldering tile the connections to the crystal detector i units mits make sure that you remove the ohp crystals us as they will be ruined by the heat or decomposed by the soldering flux for tile the sake of tane quality use fixed condensers haying having a mice mica dielectric and connect those these directly on the posts of the transformer as shown in the diagram since different transformers is vary greatly in their construction construct lon it would be worth while to experiment with tile lie capacity ot of the two fixed condensers although a it battery of 2214 2212 volts Is used to force the signals through the amplifying transformers the unit should he be built with the greatest of care as every bit of energy Is to be preserved it if the amplification Is to be successful operating amplifier in operating this amplifier connect the phone terminals of the set to the primary of tile the first transformer then carefully manipulate the first crystal lystal until the greatest volume Is obtained follow this by manipulating the second secand crystal for louder results after a little pa retice the two crystals can be worked simultaneously this amplifier although it cannot compare with the regular two stage amplifier using tubes will be free from the tube noises of the latter amplifier under good conditions a crystal set will do very good work with this unit and the locals will come in as strong as on oil the ordinary two tube regenerative receiver although the range of the receiver will not be increased Increase ilby by adding this amplifier the sign signals signal nl which were not audible will be greatly amplified and they will be heard clearly in the phones without the usual straining of ones ears it due to the location of the re celver one of these units falls to op oli crate a loud speaker two of theta should be constructed the second amp amplifier lifler should use one medium ratio transformer and one low ratio transformer it should be connected in the same way ss as the first unit and should be placed after the first unit with its input posts connected to the output posts of the first amplifier this combination will work very well in any case and for the quiet satisfaction these amplifiers give they are well worth tile the trouble I 1 e of construction a new york herald tribune |
