T&L Publications

UHF and VHF transistors are designed to operate at higher frequencies with respect to a number of specific specifications. See a data sheet for all those graphs that have frequency on the X axis. Specific methods of construction and design influence the suitability of a device to be in this category...

Check to make sure no current can flow into the gate terminal. Unless you know there is some kind of diode protection on the gate, any current flowing indicates gate oxide punch through which will often render a FET permenantly on or off (Depending on type and extent of damage). <p>What FET are you ...

As drawn the set and reset are positive and the output goes to 12V when set (remember the set and reset are backwards on my drawing). <p>The real reason I responded was that it was pointed out to me that you would also need some sort of timer on the reset as well to account for the case where you ex...

Sometimes the dumbest ideas make the most money; remember the pet rock.<p>I see it as a natural evolution of an already established market. The price is probably almost exactly the cost of such a product, so if it can be reused even one time, that constitutes a 100% profit (minus packaging and distr...

Wow, If I could sell all my home brew projects for $500 bucks a pop. Ha!<p>The PCB and controller chip looks to be a good deal though. You couldn't Fab a board like that pictured for less than $150 (total for 5 pcs) and you would have to buy 5 (probably what he did). I think it would be more fun to ...

Turn the schematic upside down and replace the ground with the battery except for RY2. It would work also if RY2 were on the other side of RY1 as well.<p>I drew it that way because most door post switches have one wire that contacts to chassis ground. To switch the hot side, you need a switch with 2...

A slope front enclosure would probably look good as a control panel. You can have the back opened up and some come with removable panels. In addition to LMB (aka LMB Heeger)also look at Bud Boxes, Serpac and Hammond enclosures. These are often stocked at many electronics retailors. I also think http...

At the core, a flip flop would work. The circuit would be continuously powered. The door frame button would serve as the set signal and the Accessory power would serve as the reset signal. Naturally you would need some other components to scale the voltage and interface to the relay but that should ...

Check out the may issue of GPS world online at the link below. There is an article about Kinematic GPS (KGPS) getting accuracies as good as 10cm. In essence they use accelerometers to provide dead reconing input to the controller while the GPS signal is obscured<p>Other issues also have articles abo...

Rick is correct, with SA turned off my recievers showed dramatic improvement in accuracy right away. That's one thing Clinton did do right. Generally the accuracy has to do with how many satellites the rcvr can see and how long you have been locked on. Military recievers use a more accurate signal c...

Just to make things a little clearer about supply names. Here is the convention as I understand it.<p>Uppercase "V" means DC voltage Lowercase "v" means AC voltage<p>In the Subscript, Two Capital same letters means primary source. VDD/VSS, VCC/VEE. A lowercase subscript is incorr...

I believe that most car chargers do have some sort of regulating circuit given that most phones want far less than 12V to charge. Overcurrent protection is an issue also. Not so much on a good battery but you wouldnt want to burn up anything because the battery is shorted. <p>The last charger I boug...

Check out this extensive tutorial
www.uoguelph.ca/~antoon/gadgets/555/555.html

I need to design a simple circuit that will give me a 20us square pulse with variable amplitude (about 0V to 1V and at least 1mA). The event will be triggered by a button push.<p>I am familiar with variable pulse-width designs using the 555 but I am not sure how to vary the output amplitude without ...

If you are correct that the signal level (volume) is too high and causing distortion the solution would be an op-amp set up for gain of less than 1 and having sufficient bandwidth (they have these for car audio in stores). However, I would expect clipping from too high of a level and this would soun...