Universal peripheral equipment (1): 8-way relay board

EIGHT-WAY RELAY BOARD Whatever they say, don"t believe that computer interfacing is within reach of the average owner of a personal micro equipped with a parallel output port Always remember that the way from CPU accu to, say, automatic control relays is a mighty long one, and stick to these beliefs until you have constructed this universal board Despite its heavy accent on versa- tility and compatibility with any type of computer having a parallel output port, the present relay controller board comprises only very few com- ponents, as can be seen from the cir- cuit diagram shown in Fig. 1. No LSI chips, dedicated I/O controllers, or handshaking hardware; the pro- posed relay controller along with a few BASIC instructions puts you in control of any of eight DIL type (reed) relays, merely using four databits from the computer"s parallel output port. A self-strobThg decoder IC3 is a Type 4099 CMOS 8-bit ad- dressable latch which can pass the logic level at the D (data) input to one ...