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Thanks everyone, I finally got it to work. I had to tweak the tank circuit at the emitter to the frequency between the 2nd and third harmonic, the third being the one I wanted. I also changed the feedback cap from 150pf to 15pf. It took a while but I finally got it, thanks to everyone who...

So what components control the frequency, if I mess too much with any of those components, the circuit just stops oscillating completely. I got this circuit of a web site that claims this is circuit should oscillate at 40.7125MHz. That tank at the emitter is tuned to 10.7MHz, and I dont' know...

http://img55.imageshack.us/img55/9171/oscweb4qa.png This is a link to my current circuit. It should be noted that I don't have too many parts available and the inductors I used were too small to achieve that value, so I had to put 4 inductors in series, which I'm pretty sure will be a problem...

Hello all, I recently ordered a 40.7125MHz crystal to make an oscillator, but I can't get it to resonate at that frequency. I first tried a simple Colpitts configuration, and it was oscillating at 1/3 the frequency. I then tried a circuit with a cap between the base and the emitter, and a tank...

Does anyone know how to simulate a colpitts oscillator on PSpice? I'm modeling the crystal with a cap and an inductor in series and both of them in parrallel with a cap but can't get it to oscillate at all. They told me to kick start it by introducing some noise by adding a VPulse source at the...

Yea, I wish I could move the antenna outside, that would make my job a lot easier but no they want it in that packaging, I'm guessing somewhere along the fire wall of the vehicle. The ground plane will be about the size of the package (about 60mm X 45mm). What i have done so far is simulate...

Sorry I hadn't been able to get back. First of all, this is for my senior design project at my university and were doing this with the sponsorship of an automotive company. With that said, we have to keep the same dimensions of their current one, and can only work on the receiver side of the...

Hello all, I'm currently working on re-designing a keyless entry system for a car to maximize its range. Right now I'm concentrating on the design of the antenna. The current system seems to have a simple brass, top loaded monople. The frequency is 315 MHz and the antenna has to fit in a small...

The curve is on this page. http://www.geocities.com/xxzeus07xx/index.html Thanks

Hi all, Do you guys know how to post pictures on here, I would really like someone who knows this stuff to take a look at this curve. HMIC21

Yea dparker213 , thats what i did. I would post the curves but I'm not sure I know how to do that. But thanks a lot I'll look into what cswilson said.

Hello all, A recently recieved a curve from a stepper motor manufacturer. It is torque (oz-in) vs. speed (rps). It also has power vs. rps on the same graph, represented by a dotted line. I thought power was torque (N-M) * Velocity(rad/s)? I do these calculations, and the power i calculate is...

I was wondering, what is the easiest way to measure torque on a 1hp dc motor? I looked on their web site, and the motor manufacturer didn't have torque vs. speed curves. All they had was something like: Torque(in-lbs): 0 35 70 Current(Amps): 2.35...

So your saying that in DC motors there torque-amp curve should be pretty linear? What about for stepper motors and dc brushless? And also a side question, when using it as a generator whats the best way to choose your load? Thanks alot, I appreciate your help.

Hello all, I have been given the task to find the motor that works best as a generator. By best I mean as far as efficiency and output power go at the lowest rpm possible. I have set up a small experiment to test a pm dc motor,a stepper and a dc brushless. I know my experiment has quite...

How much power are we talking about with that small pm motor and at what rpm more or less. By the way, thanks for helping me out, this is driving me nuts!!

Right now, I'm just working on a 1:10 scale of the actual thing. The propellor has a 1.5m radius. Rough calculations suggest hp ratings anywhere from 1/4 to 3/4. This machine is going to be put into an underwater current ranging from speeds as slow as .2m/s to close to .8m/s. As far as fish...

Hello all, I am having trouble finding a motor that can be used to power up a propeller to about 12 rpm then shut off and act as a generator with the propeller being driven by an underwater current. The obvious problem here is though we have a lot of torque, what motor can generate any...