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January 30, 2011
Tutorial - Polarity
This page introduces the schematic representation of a Diode with the Anode (+) on the Left side and the Cathode (-) on the Right side.
Then in the photographs, every example shows the Cathode (-) of the Left side and the Anode (+) on the Right side.
You should consider flipping the drawing on the photographs around such that they are uniform in their sides. It will facilitate better learning and less confusion.
about 6 years ago
I would say close to indefinitely. I wired up something like this on my breadboard. Used a 3v source to turn-on the gate (to power an LED) and then disconnected the power to the gate and the LED stayed on. I even disconnected the power and reconnected the power and the LED came on immediately with no signal to the gate. (iow, the gate [capacitor] was still holding its charge.)
To remedy this, I put a 1 MOhm (1,000,000 ohm) resistor between the gate and ground. Despite the high resistance, this still allowed the gate to turn off instantly, yet draw very little current from the signal that switches on the gate. I was able to do PWM control of my LED and everything seemed fine.
I guess if you wanted to make sure it was turning off faster, you could use something like a 10KOhm or 100KOhm resistor at the expense of drawing more current from whatever is providing your signal.
about 6 years ago
This seems like a decent power supply from the pictures, but I have to say, I’m a bit disappointed. Immediately after plugging it in and turning it on, I noticed that the Amp display had no reading. Not even 0.00 – It was just blank. I figured maybe I needed to put a load on it to get it to display, but no such luck. The Amperage screen was DOA. (ok, DOAs happen. I can forgive this.)
The power supply itself still seemed to work fine. I could dial the Voltage up and down. Although the controls seem a little “twitchy” to me. (well, maybe “sensitive” is a better word.)
Since the dial is so sensitive, this power supply could really use is a “lock” button to prevent the voltage from changing if, say, your hand accidentally bumps the dial.
The part in all of this that bugs me is the Extech support/warranty. I contacted support via email, they determined that it was indeed bad. Then I was advised to call a number to get an RMA. The woman on the phone first said it would cost me $50 to repair. I said, “hold on. I just bought this thing.” And she said, “oh, you need to send it back to the distributor if it is inside of the first 30 days.” And I asked, “well, what if it was after 30 days?” she said, “oh we’d work something out.” O_o
Quite a bugger as it will take 3 or 4 days to send back and another 3 or 4 to get a new one.
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