Subject: Hold Function for Radio Shack Frequency Counter (Did It!)
From: galen
How to add a hold function to the Radio Shack RF Frequency Counter:
Ground TP17. In the schematic, TP17 is pin one of U3, connected to
+5V thru a 47k resistor. On the circuit board, TP17 is on the display
side, just right of the lower-right corner of the IC. Grounds are about
1/4 inch below and to the right, the three non-tinned points in the large
area of metal.
I grounded TP17 directly and the display stopped. After lifting the ground,
the counter resumed counting at the beginning of a sampling cycle.
Personally, I would ground TP17 thru a 1k resistor. I haven't performed
the mod to my RS counter, since the pads are VERY small and my fine-tip
iron is at work. I will try the 1k Hold mod on Monday and give a report
(unless somebody beats me to it).
An amplifier mod to increase the sensitivity is in the works, reports to follow.
Happy Trails to You,
Galen, KF0YJ
Newsgroups: sci.electronics,rec.radio.amateur.misc,rec.radio.scanner,rec.radio.amateur.equipment,rec.radio.amateur.homebrew
From: galen
Subject: RS FREQ COUNTER HOLD MOD!!!!!!!!!
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