I need to make a circuit that limits the voltage range in two direction, my range can't fall below 3.9V and can't go over 5.3V... does anyone know how I could make this? I've been thinking about using Zeners, but I see how that would be spiffy for one direction say a 3.9Vz but once I start going the other way I'd be limited by the Zener's forward voltage... around 0.7V... which is not good...
I need to make a circuit that limits the voltage range in two direction, my range can't fall below 3.9V and can't go over 5.3V... does anyone know how I could make this? I've been thinking about using Zeners, but I see how that would be spiffy for one direction say a 3.9Vz but once I start going the other way I'd be limited by the Zener's forward voltage... around 0.7V... which is not good...
Lots of ways, one is to have two voltage rails at say 4.5V (= 3.9 + 0.6) and 4.7V (= 5.3 - 0.6), two diodes (assuming 600mV forward drop) and say a 4k7 resistor. You can refine it.
Are you saying something like... get two zeners, a 3.9 and a 5.3, put them in series with one another but pointing in opposite directions... and put that 2 zener combo in parallel with my load?
So in one direction it would be 3.9 + 0.6 and in the other direction it would be 5.3 + 0.6... basically Zener Fwd Drop + Zener Voltage in both directions...
Are Zeners ok to use in a fwd drop voltage limiting kinda way?
About the best you can do without using an op-amp. V3 has to regulate when back-fed, so R2 provides a minimum load on it. Clipping levels at both ends adjustable by varying V1 and V3.