Prior to the DM1, digital multimeters were an expensive,
novel and bulky piece of laboratory equipment, costing
rather more than the average hobbyist could afford.
Designed by AIM, an offshoot of Rodney Dale's Cambridge
Consultants Ltd, the DM1 broke new ground. It was a
small handheld unit, housed in a polypropylene case.
The device weighed only 1lb 6oz (with battery) and had
a claimed accuracy of 0.4%. Perhaps most importantly
for budget-conscious electronics fans, it cost only
£49 + tax.
It had two big disadvantages, though.
The first problem was that it had some technical drawbacks,
such as the use of the unpopular Nixie tube for the
display. The second, bigger, problem was that (as on
so many occasions over the years) Sinclair had launched
the DM1 without ensuring that sufficient production
capacity was in place. The result was that many unfortunate
customers suffered delays of, in some instances, months.
The company was driven to placing an apology in the
electronics magazines. It was perhaps less than diplomatic
to blame the customers for the problems:
You surprised us with the overwhelming demand
for our new DM1 digital multimeter - which far
exceeded even our optimistic expectations.
The result is that many of you who have placed
orders have had to wait an unacceptably long time.
For this we apologise.
All present orders will be fulfilled by the end
of August and shortly after we hope to supply
Unfortunately, by then
the flaws of the DM1 were too widely known and demand
slumped, just as Sinclair was gearing up to meet it.
In November 1974, the price was reduced to £24.95
+ tax. The reduction failed to lift flagging sales.
In hindsight, it is perhaps significant that the DM1
wasn't even mentioned in a historical account of Sinclair's
instrument business, written in 1978. Sinclair's delivery
troubles were to prove a perennnial problem for the
company, as the unhappy saga of the QL
demonstrated a decade later.