HEADPHONE LIMITER

most receivers don't provide automatic volume control on code reception. thus a CW signal that blows your headphones off one moment might lie buried on the threshold of hearing the next. the headphone limiter chops those S9-100 signals down to size until they equalize with weaker signals, giving relatively constant headphone volume. because the clipping action produces some distortion, the limiter should feed a headphone Q-peaker (described in another circuit). the value of Rx should match the existing speaker impedance and power. in most cases this will be equal to 4 ohms at 2.5 watts.


PARTS LIST FOR HEADPHONE LIMITER
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D1,D2-1N60 diode.  R1-5000-ohm audio taper potentiometer.  Rx-see text

TWO-WAY SIGNALLER

using diode switching a single pair of wires controls two circuits that normally here with lamps , the same idea can be used for telephone circuits. when polarity-reversing switch  S 1  is set so the positive battery terminal feeds the top wire, the D 1/L 1 circuit is operative and only lamp L 1 lights up. lamp L 2 remains off because diode D2 blocks the flow of DC to the lamp.

 when battery polarity is reversed. so the top wire is negative. only D2 conducts, illuminating 12.  D1 blocks the current flow and L1 is off.if a carbon mike is connected in series with the battery and the lamps are replaced with headphones, switch S1 determines which of two headphones receives the transmitted signal.

RE-USE OF CONDEMNED FLUORESCENT LAMPS

fluorescent lamps are being widely used for household lighting instead of the ordinary incandescent ones.the efficiency of a fluorescent lamp is much higher than that of a glow lamp. in a flourescent tube 50% of the electrical energy is converted into light energy, whereas in a glow-lamp only 20% of electrical energy is converted into light energy.
many of us throw away our fused  or condemned florescent lamps because we know that these are useless. but you can re-use then by modifying its circuit arrangement with the addition of two extra components. the mode of connection of a good florescent lamp is shown in fig.1 when both the filaments f-1 and f-2 or any one of then is fused the tube cannot produce light.
refer fig-2 you will nedd only one 220 ohms 10 watt resistance and one 2.5 mfd.400 volts capacitor alongwith the ballast choke and the starter.the circuit arrangement will be as per fig- 2 for 100 w tube, the value of the capacitor should be 5 mfd. 400 v.
if your fused tube lamp does not glow with this special circuit, you may try again by replacing the 220 ohms resistor by an ordinary copper wire.