I have an ac signal in the range of 1.5v-10v and it needs to be shifted down by 0.5v so it is in the range of 1v-9.5v. How can i do this exactly? assuming it uses a single power supply.
any help appreciated.
thanks
Voltage range of ac signal
acdcoffset
Related Solutions
A small 1:5 transformer will boost the voltage to the 1.5 to 2.5 V range, which will be enough to light up the LED. A current-limiting series resistor may or may not be needed, but just to be safe, make it 100 Ω to limit the current to 10 mA or so.
The LED can withstand the reverse voltage, so no other rectification should be necessary, but if you're really worried about it, just put an ordinary signal diode in parallel with the LED, pointing the other way.
simulate this circuit – Schematic created using CircuitLab
It may be possible to use a 1.5v AA battery if you are able to find relays that operate at that voltage. Relays will be the most costly part of this setup, so I'd start searching for relays that you think would operate well for your purposes. The specifications and price on the relays should be the most important consideration in building this. You'll want to find them rated at very low voltage levels as well as having comparable closed switch resistance values to what is discussed in the articles.
Looking at some relays on digikey here: http://www.digikey.com/product-search/en/relays/signal-relays-up-to-2-amps/1049448?k=relay there seem to be many relays that have a Turn-On voltage between 1.05 and 1.5 V. If you get one of them, then you can choose your circuit to operate at that low of a level. In short, find a relay you like/have/can get cheap and then build the rest of your circuit around them.
Best Answer
My understanding is that to add a positive Offset, you add a Postive DC voltage to an AC signal which gives the signal a positive offset. So to shift it down, what you will have to do is give it a negative DC voltage. You can look up how to provide negative DC to power an opamp, and use the same way to generate a voltage of -0.5V and combine it with the signal. The diode idea by Dwayne should also do the trick.
Another thing you can do is bring it down to 0, by adding a capacitor or any other way, so it fluctuates by an equal amount like normal AC around 0, and after that you can add the positive DC offset to that signal. But this will require more circuitry, but should do the trick.