Infrared switch operated by remote
SFH505A made by Siemens combine infrared diode receiver, amplifier, demodulator and a filter band pass for minimizing interferences. This circuit work together with this infrared transmitter.
The output signal of IC1 has the impulse duration limited to a maximum value. This fact is exploited by the associated transmitter for obtaine a maximum radius action. Most commercial remote controllers uses modulated data transfer, in which impulses width is smaller than that which can work IC1. Please note that remote transmitters from Sony or Philips have no effect on this circuit.
Diode D2 indicates that IC2a has received an release impulse. If interference occur due
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Autodisconnection for audio equipment
This simple circuit disconnects equipment rack of your audio in case has not delivered a sound a specified period. Circuit is operated by pressing his S1, which produces loading of C1. Further, switch IC1b AO exit in the state “up” and the audio equipment is powered from the network through semiconductor relay ISO1.
LINE OUT terminal signal of power audio amplifier is applied to the entry circuit through connector K1. Operational amplifier IC1a is configured to function as a signal detector with release threshold of approximately 50mV. Observe that potential for audio amplifier ground is high in the autodeconnecting circuit at approximately +4.5 V, through R1-R2-R3 resistors. When the audio signal is greater than 50 mV, IC1output goes in H state and T1 transistor starts to conduct. In the absence of audio signal input C1 is
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Neon tubes brightness adjustement
The brightness of a neon tube can not adjust as easily as that of a bulb with Incandescent tube because it starts only when a voltage much higher than that of the network, then remains on at electrical network voltage.
Normally, the high starting voltage is obtained by the interruption of current which circulates through a choke coil. This is usually a starter to ensure a sufficiently large current through the tube filaments.
These starter functions are taken over by circuit presented which also allows adjustment of the neon brightness.
When we switch on the neon tube, the brightness control potentiometer, P1, should be placed on the position of maximum brightness of the tube, to facilitate the start.
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