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PostHeaderIcon How A Blocking Diode Works & Testing A Diode With A Multimeter

A blocking diode is used to allow electricity to flow in one direction but block the flow in another direction. This can be compared to a one way valve. In this article I will show you how to test a diode to see if it is good or not, how a diode works, and how to use it.

I had a blocking diode fail in my wind turbine setup about a week ago. This diode was between my DC wind turbine and the battery bank. The diode allowed power to flow from the wind turbine into the batteries but blocked the flow of energy back from the batteries into the wind turbine. Without a blocking diode on a wind turbine the battery bank would just power the wind turbine like a big fan motor until the batteries were fully depleted.

How to test a blocking diode

There is a silver band on most diodes. The diode body is black. The silver bandk shows the negative side of the diode and the unmarked side is the positive side.

How to identify a diode markings

Pointing to the negative silver band on the diode

To test a diode with a multimeter, simply set the meter on the Ohms setting. Chose a mid range on the meter.

Take one of your test leads from the meter and hold it onto one of the diode wires. Do the same with the other meter lead on the other wire. If the diode is forward conducting then you will see a resistance reading. Mine was just under 20,000 Ohms. When you reverse the meter leads you should see an infinite reading, or no reading depending on your specific Ohm meter. If you get these results then your diode is good and working fine.

Testing a diode with a multi-meter

Testing a diode with a multimeter

But if your diode has failed like mine and conducting in both directions then you will see a resistance reading in both directions. This means that the diode is defective and should be disposed of. My diode actually shorted out just like a wire. It had almost no resistance at all and was conducting in both directions.

You can see the full video here: YouTube Video

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PostHeaderIcon Homemade Experimenters Power Supply Adjustable Output w/ Plexiglass Case & LEDs

Working with electronics all the time, you will need an adjustable power supply. Working off grid, means it should be able to handle anything from half a volt up to 30 volts, but be powered off of 12 Volts DC. This power supply project can house anything you want, but mine is run on solar power. The power supply case is made of clear plexiglass and has LED lighting effects, just for fun.

Homemade experimenters power supply with acrylic case and LEDs

Above is a photo taken after the LED effects were put in. I have been wanting to build a variable power supply for all my experiments. The Off Grid Project is a 32 foot camper running off solar power, so there is only a 12 volt power supply. I wanted to have a variable output power supply for testing new circuits such as my MPPT solar power controller. But do to that you need voltages ranging from 0 volts up to 30 volts DC. So I started to make a power supply and remembered that I had some acrylic sheets a friend gave me. Why not make the power supply look nice as well.

I just got some little buck inverter units from the internet so I used one to run the LEDs on the case. A dollar store neon tube meant for autos was hacked for its 12 volt cigarette lighter socket. Cheaper than buying a socket itself. This provides the power supply with all its power needs. I used two heavy bolts for the plus and minus terminals. Using ring connectors, this can then be expanded as needed easily. To add a new power supply circuit, simply screw the wires on to the bolts.

Right now this is just a pretty case with some LED lights. Later I will be adding a digital volt meter with a selector switch to show the voltage of any power unit I want to use. There will be various circuits installed into this box. A DC – DC boost circuit to provide anything above 12 volts up to 30 volts DC. Also a buck inverter will be used to supply from 12 volts down to 0 volts DC. I may add some AC circuits later as well.

As the project progresses, you can follow it here…..