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  • Users: raivo
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  1. raivo

    Constant current sources

    Thanks guys, some more questions. How paralleling of linear current sources is done? Just diode to the output of every current source before connecting it to the general output line... is it that easy? Output voltage of supply can change between 0.5 and 24V, current has to be constant if...
  2. raivo

    Constant current sources

    How are current sources made if they have to supply 50A or 500A or more? Are there such things as switchmode constant current sources? Any reading (or links) on this subject would be of great help.
  3. raivo

    Short circuit protection

    Thanks for help! Primary voltage is 220V and i talk about short circuits on secondary. I think its easyer do detect voltage on secondary because voltage is lower there and more acceptable to IC-s. Relay was considered beacause it makes easyer and faster to recover from short circuits. I also was...
  4. raivo

    Short circuit protection

    I have 220V 800W toroidal tranformer. Output is 36V. I want to use this for various experiments. I wish that it would be impossible to ruin transformer by accidental short circuit or overcurrent. I think of powering the transformer through relay and wiring some analog circuitry that detects...
  5. raivo

    How to connect ground lines?

    I have three microcontroller boards connected between two devices. Data flows through these boards from one device to another. Some calculations and transformations are done with data flow. I do not go to details as this probably is not important. For testing i used LPT port of PC 1 as sending...
  6. raivo

    CompactFlash writing speed.

    Max speed of Compact Flash (or other memory cards) is hard to define as every manufacturer tryes to make faster cards and so speeds rise rapidly. Easyest way to make data storage for data aqcuisition system is probably not by Comapct Falsh (as that needs IDE interface) but by some more modern...
  7. raivo

    Strange oscillator frequency

    Does anyone know why such a strange clock frequency as 14.31818 was used in old PC-s? This information is not practical value for me. I am just curious. Raivo
  8. raivo

    Linear CCD-s

    I deicded to experiment a bit with linear CCD-s. I have some Toshiba and NEC sensors and also got datasheets. Still it seems that i need more understanding what all these clock pulses are for. Usually at least 4 different clocks (such as phi1, phi2, RS, BT) must be supplyed and it seems that...
  9. raivo

    208 pin quad plastic processor marked 20h2558 IBM

    It is almost impossible to get any data about such chips. That chip is probably manufactured for this particular board and data sheets are never released to public. :-( regards, Raivo
  10. raivo

    I Need Xicor X20C16J NOVRAMs

    Usbid deals with out-of-production parts. Look at http://www.usbid.com. Also i think that Xicor is not only solution, as other manufacturers (such as Atmel and Samsung} may make compatible chips.
  11. raivo

    Any one try overclock a PIC microcontroller?

    I once tryed to overclock 8051 from 12 to 16 MHz and another from 16 to 20. I used theese on room temperatures and had no problems. IMHO you may try overclocking if your application is for your own use and you make some strong reliability tests before you decide that it is ok. Also i know that...
  12. raivo

    Optically isolated light dimmer

    Does anyone know of triac-based light dimmer circuit where potentiometer is optically isolataed from mains? Raivo
  13. raivo

    Low frequency electromagnetic noise

    Do you know of simple ways to measure low frequency electromagnetic noise in environment? I encountered this problem when designing some basic bioelectric transducers. I understand that sensitivity to such noises can be minimised when using differential amplifiers and 50/60Hz filters but...
  14. raivo

    Z80 Microprocessor w/ Floppy drive

    As much as i know Lewish is not right here... I browsed old data sheets of uPD765 and WD37C65 floppy disk controllers that were used on AT and XT computers. And found that both of theese are z80 compatible (as datasheet states). Even 100 pin flat packs on pentium motherboards use 8 bits for...
  15. raivo

    Vey old codec

    Thanks! Your advice helped me more than simply giving this data sheet. Freetradezone contains almost everything i ever heard about. Thanks again, Raivo
  16. raivo

    Vey old codec

    Does anyone have data sheet or at least pin descriptions of old PCM codec 2910 or 2911. These were made by Intel (prefix D) and TI (prefix TCM) ten years ago and were widely used on various digital phone systems. Hoping someone can help me with data sheet! Many thanks, Raivo
  17. raivo

    Microcontroller choice

    At first i want do know is there some parts at all near to theese specifications :-) As you know yourself i can use external AD & DA as well and to use also external DMA controller. But i'd like to get it all in one chip. Its enough of 8 bit AD ( 10 bit is ideal). Problem is to build some...
  18. raivo

    Microcontroller choice

    I need microcontroller with integrated AD & DA converter serial & parallel IO and external bus with some kind of DMA capability. Address space must be at least 4 megs. And this chip must be available in socketable package (like PLCC or PGA). Any suggestions? I know, Toshiba makes such micros but...
  19. raivo

    Anyone tried to use Compact Flash in an embedded system?

    There are many memory cards in the market and if is not essential to use Compact Flash then other cards are better. Compact flash needs costly connectors and you must drive tens of pins. SmartMedia has less than twenty pins and is much easyer to interface. MMC (MultiMediCard) can be read and...
  20. raivo

    Using dynamic RAM

    All my microcontroller projects so far use static RAM for external memory. Now i want to try dynamic RAM in one project. I have, maybe silly, question. Is it enough for reliable DRAM refresh to simply read data from every row within specified refresh interval? If so then i can simply use...

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