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AVRFreakMan's Achievements


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  1. AVRFreakMan

    FM Radio

    You should NEVER attempt to measure resistance in a powered circuit. Anyway, remove R4 and it should work. You didn't see the scissors?
  2. AVRFreakMan

    FM Radio

    Explain more! Did you use a program? What program? What OS? My program runs only in plain old DOS environment. That means DOS, Win95, Win98(SE) but not any NT based Windows. Have you measured the voltage in B point with a multimeter? Does it change in regular steps?(0 to 5V, @ 5V/255 steps) If you think everything else is correct, check parallel port's settings in BIOS. Alter SPP/ECP/EPP settings and you'll see. Report your findings and if anyone has any photos, it whould be nice to see them. Kyriakos
  3. AVRFreakMan

    FM Radio

    Found another scan image of the PCB.
  4. AVRFreakMan

    FM Radio

    I haven't done any changes in this circuit. This is my reply in MP's email notification that I got yesterday: However, I should say a few more words that may not be obvious. 1) The operation range of the varicap in this circuit is 0..5V. The BB329 works up to 32V but here is used up to 5V. This results in about 40 to 15pF.(The datasheet is wrong when it says VR=3V -> ~3pF. It should say VR=30V -> ~3pF. Check the "Capacitance versus reverse Voltage daigram".) Use a similar varicap. 2) If you decide to use the LPT option, cut the line in point "A", delete the potensiometer and connect the "B" point, to wiper's line. If you leave the pot in, you may use it for manual micro-tuning but it will introduce some unwanted voltage drop of the R2-R LADDER circuit. 3) In my prototype I used the LPT option, without any potensiometer. Furthermore, I added an op amp connected as a buffer x1 from "B" to "A", just to be sure that the R2-R LADDER circuit will work with my LPT port. However if the pot is deleted, the buffer is not necessary. P.S. Dont's ask me for the PCB layout. I tranfered the circuit by hand directly into the PCB. One time job. Kyriakos
  5. The idea is doable but I'm not convinced that you have the skills to do it. You could use a microcontroller with a touch LCD but you can't do that with C++ and Win32 API. For that convenient programming enviromment you have to use a Pentium board, like those PC104 style. It is also expandable, by bulding more consoles. One for maybe each room in the house, or in strategic places and for other cars. All these consoles should have passwords and the communication should be bidirectional with feedback/acknowledge. What kind of RF communication are you up to? You could do it with free license 433MHz or with your cell phone, via SMS/MMS but this is not free. The cell phone could also be your console and Java builders exist for smart phones. But first of all, you should start modifying the electrical system in your house, to be remotely controlable. The whole thing is not going to be cheap!
  6. Hi BOHDA, nice to hear that it works. I followed the schematic in analog section. In my experience, it looked ok. It wasn't ok, that's why it doesn't show stable/correct values? The PCB is unclear too and I was too lazy to try to extract the schematic from it! In the breadbording circuit that I made, I tried LC values around those you mention(I found them in comments in the source code) but I had no luck. Maybe it was breadborad's fault. Loosy contacts and stuff.. I'm amazed by the fact that it shows you all the characters in LCD(even separated in two lines). I couldn't reproduce that. In my circuit it shows only the first 8 chars no matter what! The advice regarding not using the RS485 was in order to keep the circuit free of RS485's spikes/noise or battery's life? That was the only section it worked for me! :) Actually I didn't use the RS485 converter, just took the Tx output from the AVR and used an RS232 converter to my PC but I could finally see what the LCD should show! I don't know if I ever try(again) to make it work. I'm actuallly looking now for a more sophisticated circuit that whould be able to measure inductance, capacitance and resistance in every component(LCR). There was such a device(construction article) in ELEKTOR's magazine some years ago('97 ?) and it had a DSP to do the job. Kyriakos
  7. Some microphones have three leads, othes have two leads. One of those leads is surely the ground(or -V or 0V or GND or Common). Both of these two categories might need supply that take from the third lead, if they have three, or from the second(which additionally serves as MIC_OUT), if they have only two. For those with 3 leads, the one that is not the VCC nor the GND, it is the MIC_OUT.
  8. This circuit is a CB transmitter, not "reciever"(the correct spelling is "receiver"). CB means Citizen's Band. There are microphones that need a small supply voltage(and limited current which is done by the help of the resistor R5) to be able to work(because they have embedded preamplifier). This is why the circuit has this option. For microphones that do not need this, you can just leave it unconnected. Kyriakos
  9. pdmr, How about this site: http://www.xs4all.nl/~barendh/Indexeng.htm It hasn't the BAT29 diode but it has many other RF schottky diodes which might suit your needs. Look under RF diodes ;-) Kyriakos
  10. AVRFreakMan

    FM Radio

    L2 is the tuning coil. Just make it: take a thin wire(0,6mm) and make 5 turns of 4mm internal diameter. If it doesn't work try to stretch/squeeze it and if it doesn't work add/remove turns and repeat.(adding turns reduces frequency). If no success, check the PCB and components for errors, or use a capacitor trimmer instead of the varicap, or search the internet and the datasheets of TDA7000 for other similar circuits. Kyriakos
  11. I gave up! It doesn't work in any way. Even though I would bypass the LCD because it has a workable connection for a PC COM port, I cannot bypass the fact that it doesn't measure any coil or capacitor. The readings seem random. :-( Kyriakos
  12. AVRFreakMan

    FM Radio

    If it cannot tune to any station, experiment with the coil. Stretch it, add more rounds...
  13. Thanx MP! Useful info. So the 16x1 LCD that I tried is actually from those 16x1A. I'll test the whole circuit with this LCD in the weekend and see if it's worth the trouble so far. Kyriakos
  14. Groovy, you haven't seen this? http://www.myplace.nu/avr/minidds/index.htm Kyriakos
  15. Well, the circuit in general is unclear as for the values of many components(L,C) but it is easy to test the digital section without building the analog. A majore error was in LCD data pins. They must be swaped. Where B0 must be B3(B0->B3,B1->B2,B2->B1,B3->B0). The rest data pins should be pushed gently down to ground. About the LCD that displays only the first 8 chars, I just used a 16x1 LCD in a circuit that needed a 20x2 LCD. It displayed the first 8 chars from the 1st line and the first 8 chars from the 2nd line in the single line that the 16x1 LCD has. So I assume that there is some confusion in initialization when you init the LCD for 1 or 2 lines. I think that if I'll try a 16x1 LCD, it is going to display the data correctly. Kyriakos P.S. >>MP What do you mean by "16x1A displays"? The letter "A" defines some special characteristics?
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