Search found 85 matches
- Fri Sep 02, 2005 9:55 pm
- Forum: General Discussion
- Topic: opto Isolator
- Replies: 15
- Views: 7093
Re: opto Isolator
In series as you have it drawn.<p>However, as it is drawn, the inputs are all active high. You need to be certain that the driving circuit can source the current and that the resistor is sized for the actual input voltage. In most cases where you pull up, the voltage will never get close to 5V.<p>It...
- Thu Sep 01, 2005 2:25 pm
- Forum: General Discussion
- Topic: PWM motor circuit and diode
- Replies: 31
- Views: 12985
Re: PWM motor circuit and diode
You might consider the Intelligent Power Switch http://tinyurl.com/b9oom They're a little pricey at $2.52 (Digikey) but all of the MOSFET driving nonsense has been dealt with.<p>You can see other devices in the Automotive section at www.irf.com
- Tue Aug 30, 2005 5:02 pm
- Forum: General Discussion
- Topic: dc motor chassis as ground
- Replies: 5
- Views: 2462
Re: dc motor chassis as ground
Why not? The starter motor in you can works the same way.<p>Now, I am assuming this is a LOW VOLTAGE motor. All bets are off if the thing is running at hundreds of volts.<p>12V or so should be fine.
- Mon Aug 29, 2005 7:55 pm
- Forum: General Discussion
- Topic: newbi question on relays
- Replies: 1
- Views: 1351
Re: newbi question on relays
Lay it upside down and use small jumpers for all of the pins. Just solder them on and remove them when you are finished.
- Mon Aug 29, 2005 6:26 pm
- Forum: General Discussion
- Topic: EM spectrum and the human body
- Replies: 6
- Views: 3000
Re: EM spectrum and the human body
There was an interesting graph in the 1994 ARRL Handbook that showed which frequencies were absorbed by the body. YOu might check your local library if you don't have a copy. Other years may be similar.<p>I doubt that it will be all that useful for your project but...<p>Where I worked, we were think...
- Fri Aug 26, 2005 8:19 pm
- Forum: General Discussion
- Topic: pulse width modulation circuit (PWM)
- Replies: 10
- Views: 4978
Re: pulse width modulation circuit (PWM)
Nobody can tell you that the circuit will work because it depends on the current requirement of the motor. You really have to specify this or everyone is guessing.<p>If you are thinking that you will use a 2N3055 (big TO3 device) because it can handle the current you will be surprised when you look ...
- Wed Aug 17, 2005 6:25 pm
- Forum: General Discussion
- Topic: Senior Design Project (EE+ME)
- Replies: 22
- Views: 11076
Re: Senior Design Project (EE+ME)
There is a project on the web for a home brew Segway and a unicycle.<p>Start here: http://www.tlb.org/scooter.html
- Sun Aug 14, 2005 12:55 am
- Forum: General Discussion
- Topic: Robot Vision (image recognition)
- Replies: 6
- Views: 3529
Re: Robot Vision (image recognition)
If you can control the lighting level and the selection of colors, color tracking with the CMU Cam will work quite well.<p>As a matter of fact, the Sumo11 version of the MiniSumo Mark III robot uses Interactive C and there is a library for handling the camera including the chasing of blue or orange ...
- Sat Aug 13, 2005 7:06 am
- Forum: General Discussion
- Topic: RPM display logic check
- Replies: 9
- Views: 3992
Re: RPM display logic check
I had read the bargraph thing earlier. It would seem that this simplifies the computation in the following way: There are only 20 possible readings between 0 and 6000 RPM or 300 RPM per bar. It should be possible to calculate the time counts that represent the center of each bar and just do a lookup...
- Fri Aug 12, 2005 5:08 pm
- Forum: General Discussion
- Topic: RPM display logic check
- Replies: 9
- Views: 3992
Re: RPM display logic check
Actually, this is a very nice solution. Then RPM = 1,200,000 / counts between pulses. But it does take a division.<p>Measuring frequency doesn't require a division but it does need pulse rate to get any kind of resolution.
- Fri Aug 12, 2005 4:13 pm
- Forum: General Discussion
- Topic: RPM display logic check
- Replies: 9
- Views: 3992
Re: RPM display logic check
My guess is that the RPM reading will be VERY sluggish. One of the ways to improve this is to sample 10 times as often and keep a 10 entry moving average. Throw out the oldest reading and keep the latest 9 plus the new reading. Unfortunately, you just don't get enough counts to make any difference.<...
- Wed Aug 10, 2005 8:27 pm
- Forum: General Discussion
- Topic: Measuring analog singal from 0v - Xv where X is unknown
- Replies: 11
- Views: 4202
Re: Measuring analog singal from 0v - Xv where X is unknown
First off, you can offset and rescale your analog voltages with an Op Amp. If you are only interested in voltages between 11 and 13 volts, simply dividing by 3 to get it in scale wastes a lot of resolution on voltages that don't occur.<p>For a 10 bit converter, if you use the entire 1024 count acros...
- Wed Aug 10, 2005 8:16 pm
- Forum: General Discussion
- Topic: programing FPGA
- Replies: 1
- Views: 1577
Re: programing FPGA
Obviously, there isn't enough detail given to make any solid recommendations but I would start looking over at www.digilentinc.com <p>Their Spartan III Starter Board is quite inexpensive and has a lot of capability. Further, there is a lot of code over at www.opencores.org Pick from what is there an...
- Sun Aug 07, 2005 9:25 pm
- Forum: General Discussion
- Topic: SWM seeks FET for high-powered relationship
- Replies: 8
- Views: 3800
Re: SWM seeks FET for high-powered relationship
You can also add a 470 ohm pull-up resistor on the gate of the IRL540N. This will help guarantee a rapid transition to full turn-on.<p>Connect the other end of the resistor to +5V.<p>This will add 10 mA of sinking current to the PIC but that is well within the pin capability.
- Sun Aug 07, 2005 2:13 pm
- Forum: General Discussion
- Topic: SWM seeks FET for high-powered relationship
- Replies: 8
- Views: 3800
Re: SWM seeks FET for high-powered relationship
Save yourself a lot of effort. Use the IRL540N from glitchbusters. It is good for 36A at 100V. But the part you care about is the fact that is is logic level triggered. You can hook it up just the way you said and it will work fine. You may need a heatsink. <p>Connect one side of your load to +12V. ...