Alternative to my transistor setup to switch 12 volt devices?

Other Hardware General Electronics
1

I am using an Arduino (powered from a small 5v battery) with a transistor as a switch to control a high current 12v device. This all works well, but it requires constant voltage from the Arduio pin to the transistor gate for the 12 volt device to stay on. This constant voltage to the transistor gate, will obviously deplete the small 5v Arduino battery if I want to keep the 12v device on for extended periods of time (hours or days).

Is there a transistor like device (does not have to be a transistor, but just have the function I want) which would work more like a light switch in a house? e.g. the Arduino would apply a voltage to the gate only ONCE and the 12v device would remain permanently on. If a voltage is applied by the Arduino ONCE again to the gate, the 12v device would turn permanently off. A similar principal to a light switch in a house e.g. there is no need to keep your finger (apply voltage analogy) pressed on the switch at all times. Does such a component exist?

2

No as far as I know. You can easily build a circuit with such functionality. Google "latching" or "latch" (i.e. latching relay) for inspiration.

Having Arduino pin HIGH or LOW does not consume current by itself. Only the Arduino running (and the driven load). How do you power down the Arduino?

3

A logic level MOSFET only consumes current when first turned on (charging gate capacitance). Once the MOSFET is fully on, no more current is drawn by the MOSFET. If you post a schematic of your current setup maybe we can suggest a better method.

4

Bipolar transistors have a base, not a gate. MOSGETs have gates. So we can't tell if you are already using a bipolar transistor or a MOSFET.

Voltages don't deplete batteries, currents do.

5

groundFungus:
A logic level MOSFET only consumes current when first turned on (charging gate capacitance). Once the MOSFET is fully on, no more current is drawn by the MOSFET. If you post a schematic of your current setup maybe we can suggest a better method.

I am using a N channel mosfett fdp6030bl

What about BJT TRANSISTORS? Do they only consume current when first turned on? My research tells me Mosfets have a much less drain on a battery.

6

BJT transistors are current operated. They will always have current flowing into (or out of) the base to keep them turned on. MOSFETs are voltage operated. Once turned on (gat capacitance charged) they will draw near 0 current. Your research is correct in that respect.

7

Is there a transistor like device (does not have to be a transistor, but just have the function I want) which would work more like a light switch in a house? e.g. the Arduino would apply a voltage to the gate only ONCE and the 12v device would remain permanently on.

Yes, it's called a thyristor. Once current is flowing it stays on until you interrupt it by some other means. You then have the problem of interrupting the current.

There is also a gate turn off thyristor , never use one, never seen anyone on here refer to one, don't know how good they are.