[GreenKeys] tuning fork frequency?

[Ken Schwieker]

There is a problem with the LED/resistor strobe circuit in that a 
LED's reverse max voltage spec (usually around 5 volts) precludes 
having the 140 volts on the non conducting half of the cycle getting 
to the led. A blocking diode should work to keep this from happening. 
Another better option would be to use a bridge rectifier which would 
in addition to solving the reverse voltage problem, give 120 blinks a 
second verses the 60 with a blocking diode. The blinks from a LED in 
these circuits will be rather drawn out which will result in a 
smeared target view. Since any useful strobe effect will work this 
probably makes no difference.

Ken S



 >Thanks for the help with the Teletype tuning fork question.
 >
 >I believe that 120VPS is the correct number for a Model 28, the 
87.6VPS number is for a Model 15.
 >
 >The LED/resistor wired across the AC line is an ingenious idea.
 >
 >Dave Ross    N7EPI