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Everything posted by scottnj

  1. I want to make a comuter speaker/mic vs headset selector switch. I want to me able to select speakers = (none, desktop speaker, headset speaker, both) mic = (none, desktop mic, headset mic) I was thinking: on/off switch for comuter speaker on/off switch for headset speaker desktop mic/headset mic selection switch on/off switch for mic mute My questions are: a) Is there any thing I can do to minimize noise added to the system (pcb layout, type of switces,...)? b) What does each section on the round plugs corespond to (where do I put my switches)? c) I want to add LEDs to indicate what is turned on, is the only way with dual pole switches? Do soundcards provide any dc power for the LEDs, or should I just use a battery? I am sure you can buy this some where but I want to make it myself.
  2. I need a 390MHz transmitter module to send a digital signal to a garage dooor reciever. Do most garage doors use amp or freq modulation? Where can I purchase this? It seems everything on the internet is 433, 900, and some in the GHz range.
  3. Nice boxes Steven, they look nice, plus easy to construct. Here is a link to your thread: http://www.electronics-lab.com/forum/index.php?topic=1469.0 I just wanted to start a thread where people put thier project box ideas and resources. I forgot to include building your own.
  4. I found some software to generate signals. Its called speclab and does a lot of other things to. http://www.qsl.net/dl4yhf/spectra1.html I liked the 2kHz-3kHz range. How different will these sound compared to a pure sine wave? I guess it doesn't really matter, since these seem like my best option. Now I just need to figure out the db.
  5. Looking in the mouser catalog, there are a lot to choose from. It looks like I may have to buy a few different ones to see what frequency sounds best. Are there any computer programs that let you enter a frequency and play it through the speakers? How loud are these things? They seem to range from 70-105db, but I don't really know how loud that is. I want to be able to easily hear it, but not be anoying. Any recomendations for a starting point so I don't spend too much $.
  6. Thanks Alun, That sounds exactly like what I need. Easier the better. I don't want it to be adjustable, I just got confused from trying to read some other web page.
  7. I have a PIC in my project, I think I can turn a pin on/off in that frequency range. Is this how the buzzers work? If so, I adjust the tone in my firmware? Can you adjust volume? I would like to minimize components and keep to a small space. The PIC can only source/sink ~25mA.
  8. A piezo buzzer will make a beep? Then why do they call it a buzzer? ;D How do you use these? Can you set the tone?
  9. What device is used to make a nice beep when you push a button?
  10. What are your favorite places to find project boxes? Who has the best assortment? Who has good prices? Who has good quality? ...
  11. What are the difference between tactile and pushbutton switches? What are the pros and cons of each?
  12. I found the manufacturer of the transmitter on the web. The spec sheet has the following info http://www.touchtronics.com/images/p814-n2.pdf So the transmitter transmits at 303MHz. After a quick search on google I found this http://www.computronics.com.au/module/txrxpair/txrx_data.pdf which will transmit at 303.875MHz. I am new to RF, should something like this work? I am guessing "Cycles = 32,400 One Second Pulses" is a typo, maybe they mean 32400 pulses/second? The 16 pin IC is just an encoder. It sends the addresses and sata out in serial. The data sheet is here http://www.freescale.com/files/rf_if/doc/data_sheet/MC145026.pdf On page 10 they have the equation for the frequency, which is set by Rtc, Ctc, and Rs. What do you think the target frequency should be, 32.4KHz, or some mutiple of 32.4k? Am I over simplifing this? Strange that the blue resistors are precision, they appear to just be pull ups for the logic of the 2 data Pins.
  13. I forgot to mention, I do not have an oscilloscope.
  14. I have a 4 button remote control. I want to incorporate this functionality into my own project. The main IC is a MC145026D, which I have found the datasheet for. I can get the same IC (dip, not surface mount). Then I guess I need to match the clock rate. I also need to find out what frequency this transmits at, then I can just find a transmitter module that matches. How can I figure out what frequency this transmits at? What is the clock rate? What are the other surface mounted components? They are: blue with numbers black with numbers light brown with what looks like Y0 brown silver
  15. Thank you so much, that website was very helpful. I read through the whole site. I didn't know about switch bounce, and how it will mess up counters (I am not that far with my breadboard yet) . I am planning on controlling the up/down with a dual throw toggle switch.
  16. What would be involved in making a garage door opener transmitter? I was planning on just buying a generic transmitter, and running some wires between my project and its switch contacts. A much cleaner solution, would be to just build one into my board. Does anyone know where I might find a schematic for a door opener transmitter?
  17. I am looking for an up/down counter that can give me a 0 to 15 bcd output. All the ones I have looked at are 0-9. I found the Maxim ICM7217AIPI which does 0-9999 plus drives the 7 segment displays, but costs ~$14 at newark and is probably overkill. Am I missing something, or just looking in the wrong places?
  18. I agree 100% with Ed, I just discovered this forum because I just began working on some projects. I think it is a wonderful source of knowledge. If you want to encourage beginners to post, I suggest adding a newbie category, add a faq as a sticky to it as well as other popular questions.
  19. thanks for the help everyone. Is there any downside to using a voltage regulator? After some reading, the lm7809 looks easy enough. I think I might also build the lm317 variable power supply, like I said, I'm bored and want to learn some things.
  20. thanks for the quick replies, this is a cool forum, too bad most of the topics are over my head. For the standard garage door buttons, I would try hooking directly up to 12v. But I have a couple specialized transmitters I do not want to risk frying. ;D I think it will be worth my effort to do this, plus a learning experiance. Not to mention, I am bored!
  21. I should have mentioned I am not an electrical engineer. :-[ If the lm7809 will work, how do I use it? Can someone draw out a circuit with whatever info I may need, plus part specs so I can buy the parts (hopefully available at my local radio shack)?
  22. In my wheelchair, I have two 12V batteries wired in series. I would like to wire a few devices directly to these batteries. The first items are a few transmitters (garage door buttons [9v battery]). What circuit do I need to put between 12/24V battery and the transmitters?
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