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Recent content by VolkerR

  1. VolkerR

    Flyback Optocoupler

    Hi, I need to design a simple flyback circuit, but I am having problems understanding the voltage regulation principle, mainly concerning the feedback optocoupler. I was googling and reading datasheets for hours, but I was not able to find an answer to my question. In most example flyback...
  2. VolkerR

    IC's for WWVB Reception at 60kHz

    Hi Skysoldier: Try the U4223B. If you google for a chip, also try "DCF77" as a searchstring, since that is the European version WWVB. It just operates on a different frequency, but also VLF. DCF77 is very popular in Europe, and you can find hobby-kits and receiver modules at various vendors...
  3. VolkerR

    Speech Synthesizer Chip

    I don't think the chip uses actual voice-samples. My first thought was 'recorded voice', too, but the chip has not very much memory. The examples on their webpage don't sound natural enough, it sounds more like something on my C64 20 years ago. They claim it has a 5 channel synthesizer, so I...
  4. VolkerR

    Speech Synthesizer Chip

    Hello, I just came across this chip: http://www.hvwtech.com/pages/products_view.asp?ProductID=505 It is being sold as "single chip voice and complex sound synthesizer". Actually, it looks to me as if it is a PIC18F1220 or 18F1320 with it's markings removed, running on the internal...
  5. VolkerR

    Battery converter

    If you want to go with an adjustable 3-terminal regulator, the LM317 in TO220 is quite popular Datasheet: http://cache.national.com/ds/LM/LM117.pdf Digikey link: http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=147559&Row=260343&Site=US But keep the current consumption in mind...
  6. VolkerR

    PIC Chip Programming

    For unknown reasons there is no cheap "5 wire to printerport" programmer for PICs, even though the newer Flash ones (PIC16F, PIC18F) do have a low-voltage programming mode that would permit it. For AVRs there is one here: http://www.qsl.net/ba1fb/avrisp.gif It works excellent and is...
  7. VolkerR

    Any one try overclock a PIC microcontroller?

    One more thing: if you just want to run a pic at 40MHz, there is no need for overclocking. Most 18Fxxx PICs are rated for 40MHz, and there are now many 18F types available with similar functionalities, partly even pincompatible to 16Fxxx devices. The 18F devices are software-kompatible, too (run...
  8. VolkerR

    Current Source/Sink Notation

    - your sink/source explaination is correct - when you are sourcing current, the current is extracted/subtracted from the output, therefore negative when you are sinking current, the current is added into the output, therefore positive. But I think it is just a definition somebody made up in the...
  9. VolkerR

    siganl processing using c++

    Try this: http://www.dspguide.com/ You can download the entire book online.
  10. VolkerR

    Relay contact cleaning

    I am not sure about that capacitor in parallel you are mentioning, but maybe you are referring to a snubber circuit ? If you are switching inductive loads, then a snubber circuit is used to soak up some of the inductive kickback, thereby reducing sparking at the relay contacts. It's usually just...
  11. VolkerR

    A digitally controlled gain for Op-Amp

    Hi Zimbali, usually the requirements call for a limited number of gain factors, e.g. 1, 10, 50, 100. In that case you can use analog switches with different attached gain resistor values. Make sure the resistor values are not too extreme, so that the analog switch doesn't introduce too much...
  12. VolkerR

    CAN vs RS485 in high RF Envronments

    In that case, it doesn't really matter. The main differences between a CAN and a RS485 transceiver: The CAN transceiver works like a RS485 transceiver, just with a dominant '0' and a recessive '1' state. The RS485 transceiver has both states dominant, therefore only one transceiver at a time...
  13. VolkerR

    CAN vs RS485 in high RF Envronments

    If you go with regular cabling, there is not too much difference between CAN and RS485 regarding noise immunity, it is more a matter of convenience. Both use twisted pair and differential drivers (CAN over fiber is possible, btw.) CAN has the protocol handling already built into the CAN engine...
  14. VolkerR

    PSK31 with a MCU ?

    Hi IRstuff Yup, but it's always about _encoding_ PSK31, mainly for beacon purposes, not about decoding from an audio signal ... Have you found PSK31 microcontroller DSP sourcecode ?!? What are your search-keywords ?
  15. VolkerR

    PSK31 with a MCU ?

    I was wondering if anybody has experience with implementing PSK31 (a fairly new amateur radio mode) in a microcontroller. Specifically, would it be possible to use a SSB capable short wave receiver and some hardware to listen to PSK31 conversations on an LC-display, without a PC ? The amateur...
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