rather than letter markings for the DC and AC switches (Basic ranges to 10 A and 3000 V). 20,000 ohms/volt DC, 1000 ohms/volt AC. (The features of the Models 8 and 9 were combined from the Model 8 Mark V of 1972, when the Model 9 was discontinued). Special Purpose Multimeters AVOmeter model 12: Designed for automotive use. (Ranges 3.6 A & 36 A, 9 V, 18 V & 36 V DC, current ranges extendable with accessory shunts), 9 V, 18 V, 90 V & 360 V (AC). Heavy Duty AVOmeter: A smaller rugged multimeter with a single selector switch. Originally designed at the request of the Great Western Railway for railway signalling purposes but first supplied after the GWR became the Western Region of British Railways in 1948. Later also sold with alternative ranges for the commercial market. (Basic ranges to 10 A and 1000 V). "Minor" Models AVOminor (1935 to 1952) - A small instrument with direct current, direct voltage and resistance ranges only. Ranges selected by plugging leads into required socket. Universal AVOminor (1936 to 1952) - A small instrument with AC & DC ranges selected by plugging leads into required socket. AVO Multiminor: Replacement for earlier 'Minor' AVOmeters. All ranges and functions selected by a single rotary switch. No automatic protection. A smaller version similar in size to small portable test meters. (Basic ranges to 1 A, DC only and 1000 V, both extendable with external multiplier and shunts). 10,000 ohms/volt DC, 1000 ohms/volt AC. Clamp meter: Principally for higher currents (Ranges 300 A, 600 A, 1200 A, 150 V, 300 V & 600 V all AC only). Sensitivity unknown. All current and voltage ranges for above are both AC and DC unless otherwise stated. Other products The company manufactured geiger counters for civil defence use during the 1950s and 60s. The Automatic Coil Winder & Electrical Equipment Co. Ltd. made many other types of instruments, including a line of valve (vacuum tube) testers. References External links Model 7 Avometer Model 8 Avometer Electronic test equipment Electrical test equipment