EPROM eraser - with radiation counter

july/august 1984 with radiation counter All that"s required to erase an EPROM is basically an ultraviolet (UV) lamp which radiates the EPROM window at the right distance (about 2 . . . 3 cm) for a period which depends on the manufacturer (normally 10 . . . 40 minutes). As we don"t think you"ll want to sit around 1 Trl gazing at your wristwatch while all this is going on, we have designed a timer which automatically ensures the correct radiation time and in- dicates the end of the erasure period. The counter-IC, type 4060, has an in- tegral oscillator the frequencyl of which is determined by R2, R3, P1, and C3. When the supply is switched on, IC2 receives a reset pulse from C5 which makes it start counting. Outputs Q12 . . . Q14 are logic low, and T1 and T2 conduct. When S2 is closed (see below), relay Re1 is actuated and the UV lamp is switched on. In addition, red LED D2 lights. The base of T3 is connected to the positive supply line via T2 so that T3 is cut off. After the time s...