voltage multiplier

Ok so I have ripped out a circuit from a toy I found and what it does is the when someone walks in front of the sensor it gives off a slow ac current at about 1.78 volts per second. Now I want to get this up to 4.5 volts. Dc or ac I don't care but it has to power 2 very large leds. Any thing will help but please try and keep the cost down,thanks.

Sincerly, Riley

it gives off a slow ac current at about 1.78 volts per second.

Sorry but that is nonsense. Does it perhaps give a 1.78 volt peak to peak signal at some other frequency?

hey sorry i'm a little new at electronics and dont really understand your question sorry. But it max "peak" is 1.78 then it drops to 0.

Run the signal into a voltage comparator, the comparator can drive the signal to +5/0V for you. That 5V can then be used to drive a transistor or something to control the LEDs. See the LM358D part on the top left of the Uno Schematic as an example, where Vin/2 is compared to 3.3V.