Problem with the IC2 or LT1054

[hisoka147]

I don't really know the function of the LT1054, basing on the data sheet it is a "Switched-Capacitor Voltage Converter".
However, even without this IC the detector function as normally as it is. Can someone help me figure out the effect of this IC from the circuit.

[bklein]

It will maintain a relative constant output voltage as the battery voltage drops quite low. Try substituting a variable DC supply for the battery and dropping it down while testing the circuit and you'll see what I mean. It greatly helps maintain a stable circuit as battery voltage drops.

Barry

[hisoka147]

I see thanks for the explanation but how about using a voltage regulator instead of that instinct type of an IC?

[bklein]

The part used here could be termed a regulator of sorts as it will maintain roughly the same output voltage as the input voltage drops. It is an open loop output by the looks of it though and for pretty small loads. There are switching regulators that can do the same thing only better - keep a more consistant output voltage over a wide range of input voltages and output loads. But they cost more. If this circuit works this is likely the cheapest approach. The others will require additional parts like diodes, inductors, and maybe switching fets. Linear regulators would maintain a lower voltage - like say +/- 5V with associated +/- input voltages but they are not efficient = more battery drain. Linears also have a dropout voltage where if the input drops that much over the output, the output goes out of regulation. So you would likely go for 5V output and expect the 12V maybe to drop to as low as 8V - but that is a lot of wasted energy dropping 12V to 5V. Switching regulator parts are getting very cheap in volume, and much commercial stuff is getting energy conscious as well as cost conscious and use them. For small volume guys like us though the parts costs can add up. Just the inductor can cost a buck but would be like 10 cents in volume.

[hisoka147]

Thanks again, I see now the difference. So this is the reason why the circuit still operates as normal even without the "Switch Capacitor Voltage Converter" since I'm not yet using a battery.

[danny475bek]

hi

use the icl7660 it is more bater and cheeper
tc
danny