Re: Accesory Counters
I think those were the DM40, DM43, and DM44 digital multimeters. Whentoggle quoted messageShow quoted text
used on a 464, 465, 466, 475, or 475A, they also read out the delay
time and the DM44 also reads out 1/t for frequency.
So the DM44 provides a frequency readout but not in the same way as a
frequency counter. What it does is measure delay and delta delay time
which can then be displayed as 1/time for frequency. This is the same
measurement which would normally be done manually using the mechanical
counter on the delay time control and when the DM option was included
with the oscilloscope, the mechanical counter was left off. Frequency
accuracy is only like 2% (from the specifications) because it is an
analog measurement which depends on the horizontal sweep accuracy.
The 7000 series mainframes display the same delay time and delta delay
time values on their readout with the 7B85 and 7B15 delta delay
timebases. The 22xx series DSOs also read out delay time on the CRT
but use cursor measurements for time and frequency.
A DM44 can be retrofitted to a 475 but I doubt a DM44 can be found
which is not already part of an existing oscilloscope. I assume there
was an instruction manual for this but it can be figured out from the
existing service manuals for the DM44 and 475.
If you want accurate frequency measurements with lots of digits, then
the 2236, 2236A, 2247A, and 2252 have a real built in frequency
counter which can make time and frequency measurements on any point of
a waveform. An external alternative is to use a universal reciprocal
counter like a DC509 or DC510 which can be connected to the B gate and
vertical outputs on the back of the 475.
On Fri, 4 Nov 2016 02:48:20 +0000, you wrote:
I remember frequency displays that mounted on the tops of scopes.