measuring with the BBC micro

The BBC micro, one of the best value- for-money computers on the market, can be used for a variety of appli- cations thanks to the various inter- faces provided as standard. The four analogue inputs, each with a resol- ution of 10 bits, make it particularly suitable for measuring all kinds of pro- cesses. There is unfortunately one drawback: the rather poor reference voltage associated with the analogue inputs. That voltage is obtained from three normal diodes connected in series. The alternative described here has been in use in our BBC micro for some time. D8 D7 3x Ds 1N4148 85494 EOC R171 100R +5V measuring with the BBC micro NRDS11.---% RD "P• mawR Rh 5V .411--H0 TVST B •4111--43 9 NOV4/111—)2 V 4111---0 10 WDS,SO 15 D7 18 VREF 19 20 21 22 CI 27 CH3 2K7 C25 C27 33n F 1pF 4 10 1 12 13 9 OV 28 ADC pa.= CS CHO AGND IMHZE adj. 6 IC73 17 pP07002 / g 0 N4148x De 41111—K)3 11 PADDLE 0 4 AND LIGHT 0 12 PEN CONNECTOR 1046÷-013 SK6 OV•411106 014 0 ; 15 ._,• 262 AO „ 0 EOC...