T&L Publications

Hi Joe<p>I have a few questions for you; - What do you mean by "15 Volts hold off when not being gated". - Are there chips specialy made to drive igbt's? Right now, I am driving mine through some cmos nand gates and I have a power supply just to drive the gates of the igbt's - Do you use o...

IGBTs are something new to me too. Although they have been around for over 20 years, there doesn't seem to be a lot of people that are familiar with them. IGBT goes for Insulated Gate Bipolar Transistor, they combine the best of both world, they can drive heavy current like bipolar transistor and ar...

I am trying to work with an "H" bridge,(I think that's how it's called) and I realise that I need more information. I am using four identical IGBT to make an "H" bride to control the primary of a transformer I am planning to use to make a TIG welding machine. The first problem I ...

Thanks for everybody's input. I am sorry I didn't thank everybody before, I was working on a project and didn't spend much time reading the posts on Nuts and Volts' forum the last few days. I was hoping that somebody on this forum would be familiar with the systems that are dedicated for heating, co...

The ring signal (90 Volts 20 Hertz) is sent by the phone company's central office so it has nothing to do with who calls you. You could try and check your phones one by one when it rings by putting your oscilloscope on and see if the ring signal gets dampened, then you could tell if you have a fault...

I think that you can run the test from any phone outlet and if it is bad there, try it at the protector (the main telephone box), if it is good there and bad elsewhere the problem is in the house wiring. Also, new electronic phone draw much less current than the old bell phone, so it is less likely ...

It could be a transistor, a FET or something else than points, I was talking about points as an example. There is a good chance that you will find your kind of ignition in his book, if you can figure out what kind you have. In some case a better ignition can make a noticeable improvement. I am invol...

When all your phones are hooked, you should get about 50 Volts DC, when it off the hook, you should get 6 Volts DC or less, depending how much load you have on your line (how many phones). When the phones are ringing, you should get 90 Volts AC at 20 Hertz added to the 50 Volts DC. You should be abl...

Is the PhD you are referring to Mr. Christopher A. Jacobs? If you look in his book you will see that ignition occurs either through charge or discharge of the coil. This charge or discharge usually happens through a capacitor. If the coil produces a spark while discharging, it is discharging through...

When I used to contact Tech Support, I was always dealing with the same guy and he was very very good, but it seems to have changed and I am not getting any good answer from them yet, I suppose that they will ajust....

I have done a circuit involving a PWM for a friend and the frequency was very stable. I noticed that you put the label BEGIN at the top of the list of code, I don't know if it is like that in the program but it is recommended that the label is at the very left of a column and the codes should be a f...

I program my microcontroller with an modified project I got form an article in Poptronics, so imagine the fun I have....Recently, I started a new project and my MPLAB 6.40, that I just reloaded in another computer, didn't work, it took me about 4 hours to find the problem only to find out that I cou...

Hi Mike<p> I am no expert in .asm but I do a little programming from time to time so some of my comments might not help.... I have downloaded MPLAB 7.00 recently and I ran into some problems with the debugger when I tried to use the "Stimulus" function. I contacted their Tech Support and t...

The main idea of using a central controller is that everything is controlled by authorized personal, it avoids having people playing with thermostat. Some of these controllers have remote access. If you have a guy that is working on a Saturday, for example, you can program the heat to come on in his...

I have used X-10 before but it is not flexible enough for this purpose. There are companies that makes systems specially designed for this purpose, like KMC, Reliable to name a few. It seems there quite a few of them and there are a few different protocol also, like Lon Work and BACNET. I was wonder...