{"product_id":"ww1-800-cycles-testing-set-acoustic-oscillator-no-10-telephone-tester","title":"WW1 800 Cycles Testing Set Acoustic Oscillator No.10 Telephone Tester","description":"\u003ch1\u003eWW1 800 Cycles Testing Set Acoustic Oscillator No.10 Telephone Tester\u003c\/h1\u003e\n\u003cp\u003eThis amazing looking piece of vintage military scientific instrument is a WW1 800 Cycles Testing Set Acoustic Oscillator No.10 Telephone Tester, and it is a real enigma. We believe it was probably made by Marconi but there are no manufacturer's label or marks to confirm this.\u003c\/p\u003e\n\u003cp\u003eAn expert advised us that this instrument dates to WW1 and would have been used for testing trench telephone lines but we have no provenance for this. However, it is fitted with a \u003cmeta charset=\"utf-8\"\u003e1920s PM2 valve, which obviously postdates WW1. It may well be that the standard British B4 valve base had a bright emitter valve fitted which was replaced with the PM2 in subsequent years.\u003c\/p\u003e\n\u003cp\u003eThis interesting test kit contains a brass vibrator, which transforms DC power into AC waveform.\u003c\/p\u003e\n\u003cp\u003eIt measures in Periods\/sec, which is an arcane unit for cycles\/sec or Hertz.\u003c\/p\u003e\n\u003cp\u003eIt has a label which states:-\u003c\/p\u003e\n\u003cp\u003e\u003cem\u003eThis instrument produces an approximately pure note of frequency, about 800 Periods per Sec, in telephones connected directly or indirectly to the terminals marked 'Signals.' \u003c\/em\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cmeta charset=\"utf-8\"\u003e\u003cspan\u003eAn \u003c\/span\u003e\u003cspan class=\"block\"\u003eAudio Oscillator\u003c\/span\u003e\u003cspan\u003e generates tunable waveforms and are used, for example, in the generation of test signals for test benches, and the generation of control signals for audio effects. \u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003eA lovely piece of \u003ca href=\"https:\/\/mullardantiques.co.uk\/collections\/morse-keys-telephony-telegraphy\" rel=\"noopener noreferrer\" target=\"_blank\"\u003evintage telegraphy technology\u003c\/a\u003e!\u003c\/p\u003e","brand":"Unknown","offers":[{"title":"Default Title","offer_id":56574738268535,"sku":null,"price":292.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0303\/5122\/8972\/files\/WW1_800_Cycles_Testing_Set_Acoustic_Oscillator_No.10.jpg?v=1768919233","url":"https:\/\/mullardantiques.co.uk\/en-us\/products\/ww1-800-cycles-testing-set-acoustic-oscillator-no-10-telephone-tester","provider":"Mullard Antiques and Collectibles","version":"1.0","type":"link"}