Recent content by jbord39

Hey an updated (an better) schematic is in the attachments. The tuning pot is used to make sure the output is right around 38kHz. The receiver (output is HIGH with no input and LOW whenever it receives 38kHz, from Radioshack) is hooked up to a 555 timer in monostable mode (this produces a...

I am back! About the mistakes in the circuit, I had just started designing electronics (I had just started college). The green LED should be connected to 5V instead of ground on one end. Also the reason for 5V as opposed to 9V is to prevent changes in the circuit functioning (like...

We're trying to include the heat flux from the metal powder inside to the air outside. Heat is generated as hydrogen is absorbed by the powder. Thanks, John

I am in way over my head, but I didn't choose where I was put. The problem is, that I also don't know anything about fluid mechanics, mass balance, thermodynamics, or chemistry. Does anyone know where I should start to get a very, very basic grasp of these. I don't actually have to solve...

Thanks. I don't have exact answers to your questions but here is the setup as I understand it. Here is what I know: The basic idea is there is a cylindrical shell filled with metal alloy powder which absorbs hydrogen. Hydrogen is pumped into the center of the tank. As the hydrogen is...

Hey guys, I am completely stumped right now (in many different ways). I am a senior in Electrical Engineering and just started an internship this summer. Sadly, they put me in a setting which involves nothing I have studied except the pure math (there is not a volt or ampere that I have...

Hey all, I am trying to create a type of current source to switch between 10 mA and 1.4 A at some frequency. I have an idea to use a BJT transistor as a variable resistor in a LM317 (or whatever the high current version is) but am not sure how to do it. Any suggestions? This circuit is to...

Thanks for the help I am looking into those now.

Well I do not want to copy someone elses circuit but using examples is certainly helpful. Since I am doing this to learn about RF in some way it seems silly to buy one already built.

Thanks. Do you know of any actual schematics? I do not want to just move around parts but rather build one from scratch.

A radio frequency control. The range would preferably be 100+ yards.

Hey all, I am trying to make a simple remote controlled switch (without any digital IC's) and was wondering if anyone knew of any schematics, etc. Thanks, John

I am currently a Junior in college studying Electrical and Computer engineering. As far as preparing you for college (as far as the things that seem important to me) are: 1. Properties of logs and exponents. 2. Properties of waves 3. The unit circle 4. Maybe the fundamentals of electricity...

Yeah that's correct. If your motor needs more than 200mA you might need a transistor.

You want to use pulse-width modulation. You can variably change the motors speed by changing the "duty-cycle" of the square wave output from the 555. Here is a simple schematic which will vary the frequency as well as the duty cycle, although that shouldn't make much of a difference (the %...