MP

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  1. Inverter

    Bose: The buzz sound that you heard was caused from not using a large enough transformer. Freerider: There are much better inverter designs on the web, which will give you much better satisfaction. I would rate this project as a learning project for basic inverter design. Years ago, Delco introduced a very similar design to this one in the US which was mounted on the inner fender well of your car and gave you 120VAC to run appliances from your car. These were also very primitive and barely useful. However, they did sell a lot of them. MP
  2. Digital Oscilloscope with PIC18F2550

    For those wanting to see the original website and the author's Q/A for the project, the URL is here: http://www.semifluid.com/?p=15 PIC Code is in C but the hex is also provided. MP
  3. Please do not post IC requests to the Projects Q/A forum. It is for discussion of projects found on our site. I have moved this topic to the correct forum. MP
  4. Microphone Echo/delay IC datasheet.

    You won't get much resolution without specialized chips. Here is an article about a simple form of audio delay using 1 bit ADC. Perhaps this will help. http://www.elecdesign.com/Articles/Index.cfm?AD=1&ArticleID=8056 MP
  5. An LM7805 will work fine in your automotive application. You could also use a LM78L05 which has a smaller package. You will certainly need the capacitors on input and output. For the input, it depends on how clean the DC12 is. I have never seen a car generate a real clean DC voltage, so I would recommend that you go with a fairly large value on the input. On the output, you will want a 0.1 uf in parallel with a larger value such as 10 uf, both bypassed to ground. If you don't have a 10 uf, use anything from 4.7 to 100 uf. This is not a critical application and you have a lot of latitude to play with here. For your application, I doubt that you will see any difference. Also, I don't mean to change your thoughts on the design, but if you are only using the voltage as a trigger, you could also use a comparator chip to do this. MP
  6. this is the most dead forum ever

    I see posts on a daily basis.....where are you looking? MP
  7. digital voltmeter using icl7107

    There are a few specific applications where you can use the ICL7107 on a single 5 volt supply instead of dual +/- 5V supply. These specific conditons are discussed in the data sheet. Check the data sheet to see if your specific application will work with this voltage configuration. It is not hard to generate the negative supply. You can generate the negative voltage with just a feww added components on the board. MP
  8. TJ, Correct on both questions. I recommend that you stay under 5 mA. I normally use 5V through a 4K7 ohm resistor as a parallel port pin high. For best results you do not want to float the pin in any state. You should insure it always has a 0V or 5V level by tying the port pin high or low. Otherwise it might float into an unstable voltage and report incorrectly. Additonal note: The car battery is not a true 12 volt source. Rarely will you see a good automotive battery read 12 volts. It is usually closer to 14. You want to make sure you do not exceed the 5 volts to the parallel port. Add a zener diode for protection if needed or use a 5 volt regulator. An opto-coupler would also be an alternative. Exceeding 5 volts to the parallel port could damage it. MP
  9. When you use your resistive divider to drop the voltage down to 5 volts, you just need to select values of resistors to limit the current. This is basic ohm's law. V/R. Was this your question or did I misunderstand? I am not sure how you intend to monitor status by using one 5 volt pin. As an interface to the parallel port, you could use an LM3914. This would give you the resolution you need. There are also many other ways to proceed. You need to convert from analog to digital to read anything useful from the parallel port. MP
  10. NEW GUY NEEDS HELP

    The Basic Stamp is just a PIC with the crystal, an eeprom, and some transistor drivers for serial comm on a board that is sold as a module. You can duplicate the pieces and breadboard all of your projects or make them on vero-board for much less. The good side of buying a Stamp is that Parallax gives you lots of support. Since you have invested in the Stamp, I recommend that you look at the schematic for your kit and make up some boards with a 20 MHZ resonator and a PIC 16C57-20. If you don't need the EEprom for a project, leave it out of the design. Only incorporate into the design the resistors you need for the input and output ports. In your kit, you have a surface mount chip. You can purchase the DIP version and use a socket. You can also socket the resonator if you want to experiment with different speeds. Here is a link to the pdf manual to what I think might be your kit. http://parallax.com/dl/docs/prod/boards/HomeWorkBoardManual-v1.2.pdf If you use the schematic as a starting point to build up your own personal project boards, you won't be limited to the "one at a time" limitations of your stamp. Hope this helps you. MP
  11. Free sample chips!

    Jack, Everyone gives away the assembly code programming compilers. There are also many free C compilers, but they are very specific to the brand of chip you use. For example, you would need a different compiler for PIC than you would need for AVR if you write in C. Actually, you would use different instructions in asm, too. The reason is that the different micros have different instruction sets and different hardware, etc. The micro manufacturers seem to cater to different parts of the world. AVR is easy to get samples in the US whereas it is hard to get free samples in some other Countries where PIC is easier to get for free. Just go their websites and ask. If you can get free samples, they will put a distributor in touch with you. MP
  12. Gas detector

    Here is a link to the manufacturer's website that makes the sensor in ante's link. All of the spec sheets are here. This is a figaro sensor. Good quality sensors. You can get different sensors for different applications, but you need to look at the application notes since they do not all have the same type of output. http://www.figarosensor.com/gaslist.html MP
  13. Making DAC with 0808

    Just use R2R ladder and an output buffer or op-amp. MP
  14. Free sample chips!

    You don't need a programming board for Atmel AVR. Just make a programming cable and use one of the free C compilers found on the web. MP
  15. synthesizer problems

    Topic moved. Posted in wrong forum. Projects Q/A is reserved for discussion of projects in this site's project section. MP