Counter Step No

Now that Peter Stark has had his fine counter "Lily Gilded" in your last issue I have an idea that f incorporated when I built mine last summer and you get it almost for free.

1 noticed that the LED readouts on digital calculators all had decimal points that could be moved at will with a switch. Looking at the specs for the Man-1 LED readout in my counter, I saw that pin six was the decimal point cathode which would light if grounded through a 220 ohm resistor.

The decimal point should light only with the kHz/Hz switch in the Hz position and with three digits to the right of the decimal point with the Hi/Lo switch in the Lo position, and with two digits to the right with the Hi/Lo switch in the Hi position.

Replace the SPST ikHz/Hz with a DPDT. Ground the center of the added section through a 220 ohm % watt resistor. From the circuit that is completed with the switch in the Hi position run a lead to the center of an additional section of the Hi/Lo switch which is now a Triple-pole DT instead of DPDT. The other terminals of the added switch section have leads to pin six of the center readout for "Lo" and the next readout to the right for IHi„

It is nice to have the decimal point show up without having to think about it each time, particularly in the right place!

If one wanted to be really chintzy one could arrange to have the decimal point on the leftmost readout serve as an over-range indicator instead of a separate LED,

Edson B. SnowW2UN Rochester, New York r

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