Quality Electronic Equipment
Technical Details and Dimensions
48 Series Switchers

Both the 48B-2W and 48B-4W switchers use a common case and printed circuit. In the 48B-2W type two outputs are omitted and the space used to accommodate the two larger relays needed to give the increased current rating of 10 amp.

The standard servo output from the receiver is in the form of a repeated pulse which varies in duration or width, known as 'pulse width modulation' (P.W.M.). The duration varies between about 1 and 2 milliseconds, the actual duration representing the position of the control stick. The switcher circuit uses a time to voltage converter to convert the pulse into a voltage representing the position of the control stick. This voltage is then compared to pre-set threshold levels in order to operate the appropriate relay.

If the signal is lost the time to voltage converter ceases to operate and it's output can be biased to a particular level. In 'standard mode', a programming link sets this to the level of the stick centre position so that all the relays turn off. For 'submarine mode' the link is removed so that the biased level corresponds to minimum pulse length with relay A turned on.