UM66 Simple Offline Telephone Tester

This is Simple Offline Telephone Tester using IC UM66, Components X1, X2 = 230V AC Primary to 12V-012V, 500mA, Sec Transformer D1, D2, D3, D4 = 1N4007 D5 = 1N5408 R1 = 270 Ω C1 = 1000μ, 63V C2 = 1000μ, 25V R2, R3 = 1,2 KΩ R4…

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