Here is a small device for HAM amateurs, how using powerpole connectors to connect ham gear to unknown power supply with powerpole connector. But you can use this tester in car as well to test battery charge level.

When you need to connect you gear to unknown source then you risk to blow your radio. This small circuit I designed to be very cheap. This tester you connect first to unknown powerpole connector and test polarity and voltage level. If anything going wrong then you just blow your cheep tester and not your expensive radio. 

When you connect powerpole tester to unknown powerpole connector then first check polarity, if polarity is wrong then flash red colour led, if polarity is right then check voltage level. Dependent of voltage level different colour glowing a bi-colour LED.

Default Voltage Levels:
Amber(Orange)  <11.5V
Green                   >11.5V - <15V
Red                      >15V

You can change voltage levels if you want in microcontroller source code.

Step 1: Schematic

Here is a schematic.

Input connector and Power Supply
CONN1 is a input connector. From CONN1 connector get power a circuit and as well measure input voltage. Input D1 - D4 diode's are connected in Gratze bridge, this is important to we have always correct polarity power supply to the circuit. Power supply is standard 78L05 IC and couple capacitor.

Voltage Divider
R1 and R2 divide input voltage to A/D working voltage range. In this resistor setup you can use till 20V. If you need higher or lower input voltage range, you need to recalculate R1 and R2 value.

PIC12F675 - A/D Converter, Comparator, LED Driver
In PIC running the Anderson Powerpole Polarity and Voltage Tester software. The software is written in JAL programing language. First read A/D converter, after compare A/D value with user defined comparator toggle levels and finally pull down to GND LED's Cathode.

"Display" Bi-color Led
Whit one bi-color led you can read status of the comparator.

Default Comparator Trigger Levels and led colors:
Low Voltage (Amber/Orange Led)  -  <11.5V
In Range (Green Led)    -  >11.5V - <15V
High Voltage (Red Led) - >15V
Wrong Polarity - Flashing Red Led

<p>so nice but how can be made with analog circuitry ? maybe an opamp, transistors, etc ? could be good to make a simpler and with recycled components version ! best regards</p>
<p>This is an upgrade to the High Sierra StopLight which retails around $15 and is basically a two-color two-pin LED wired up with a resistor across one of the legs to a PowerPole connector. You should certainly be able to build this for the same price.</p><p>If you want to build a StopLight analogue for pennies over the cost of the PowerPole connector, you could use common single-color red and green LEDs&mdash;wire them up with opposite polarities and connect about a 680 ohm resistor or so between one &quot;side&quot; and the power connector. Convention says the resistor should be on the +V side, but it actually works either way.</p>
You got a run of these done at itead didn't you?<br>I've had a PCB sitting on my desk for months that I got from their open PCB option. I thought the circuit in the thumbnail for this instructable looked familiar.
Have you found something to mount this circuit into? &nbsp; A case of some type?<br>
Nice!<br>One remark though: the measured voltage will be offset by the drop in the ground diode (D2 or D4); you might want to add that to the calibration code for more precise thresholds :)
Hi,<br><br>Thanks for note. You are right. I will add D2 or D4 offset voltage to code.<br><br>Rudolf
Hey this is quite cool, rated it 4*, and might throw a vote this way when the contests voting period starts, have a look at my ible entered for this contest<br>Thanks
HI,<br><br>Thanks for rating!

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