I am looking for a chip that will enable me to input 3-12 V DC on 2 pins (+ and ground input), to get as output on 2 other pins, the exact voltage i put in those previous 2 input pins (+ and ground output) and to have a 5th pin, that if i put in a 3-12 V DC signal - Will turn on and off the electricity that goes between the previous 4 pins (+ and ground input and output).
I understand that maybe such a chip can be found on Motorola chip series MC140xx or 74HCxx or on the LMxxx (which is not Motorola, but another manufacturer, that starts with the letter N - i forgot its name).
Anyway - i need the chip to be as less expensive as possible.
On a second thought, I am used to read about relay switch in relation to 110-220V AC. If a relay switch can do the same for 3-12V DC, i guess it could be good as well. That is - if it can be not big and not expensive - something like a mass produced chip.
I am trying to build a circuit to protect my 1000-2000 mAh 2-3S LiPos, from over discharging. I am using also an Arduino uno and Low voltage LiPo alarm buzzers - and at the end point i have several small servos. I think that the problems with all these chips, is that although on the logic and analog side, they do exactly what i need, but they will not be able to stand such a current as the LiPos let out. So i started searching for relays - but relays that have DC voltage of around 3-20V, not only for logic, but also 3-20 V DC for load - are kind of rare and expensive. I found mostly relays that are manufactured by opto22 - but too pricy.
Making an electronic switch that passes 2A to a load isn’t that big a deal. Do you want the switch to open when this other 3-12V signal is applied or do you want the switch to be closed, with current flowing, when the signal is present and then have the switch open when the signal goes away ? Also is the on/off signal originating from the Uno, is it (can it) be a logic level signal from the Uno directly ? How/where does the Uno get it’s power from and do do you want it’s power, indeed all power, derived from the LiPos to go away when the voltage goes below some threshold (presumably measured by the Uno) ? The question I’m trying to understand is how, if, the circuit must latch the power to be off and do it w/o using any power ? Alternately if the power is off be default unless the Uno measures some “good” voltage, how does the Uno get it’s power initially to make that measurement ? A diagram of how all the components in your system gets their power would be useful.
what is the load? You say you have 1 and 2 amp batteries, I assume your load is 5ish amps?
You’ll be best off using a voltage divider on the arduino to sense vBat, then have it trigger a relay with a low current 5V coil to disconnect the batteries.
If such a relay doesn’t use, you’ll want to use a transistor to toggle the relay.
You could use a mosfet to trigger the load directly if it’s a 2 amp or less load. 3 amps I’d be leary. 4 amps or more, I’d go straight to a relay, just due to heat concerns in a TO-220 package.
Also, question:
If it is a low current draw, isn’t there a way to make a voltage divider into a transistor/FET such that when the base/gate voltage drops below a certain voltage, the Emitter-Collector/Source-Drain circuit cuts out?