Search results

  1. HellasTechn

    Resistor Value.

    after doing so, it is impossible to get a steady reading and now from one lead to the other the dmm measures 30Mohm...
  2. HellasTechn

    Resistor Value.

    Will do ! P.S. with a magnifier glass it shows Green, Brown, Black,Gold, Brown. It is the camera that makes brown look like black.
  3. HellasTechn

    Resistor Value.

    Hello ! Could someone please tell me the value of this resistor ? Colours right are : Brown, Black, Gold, Brown. The DMM reads 30.1Kohm but the resistor is slightly deformed and i am not sure if the value has shifted. THANKYOU.
  4. HellasTechn

    Simple Uninterrupted Power Supply Circuit

    A simple relay can do that, driven from your power input. when power is present it can direct it to the pi and charging circuit. when power is removed the contacts can route battery power to the pi. :)
  5. HellasTechn

    +15V supply shorted

    Why do you suspect the tantalum and not the Vreg itself ? Ok now i see why :p
  6. HellasTechn

    RS232 - RS422 CONVERTER

    Thank you all !!!
  7. HellasTechn

    RS232 - RS422 CONVERTER

    Since my knowledge about serial communication is very limited, the next question that pops into my mind is this: is the rs485 standard compatible with the rs422 ? Can i use and wire the above converter as i would with an rs232 to rs422 ? I searched and found this...
  8. HellasTechn

    RS232 - RS422 CONVERTER

    Okay i think i know now what the confusion is. I should have explained better. I need the converter to to enable my laptop to receive rs422 and also transmit rs422 to devices such as GPS and compass. Why do i need that ? because i try to figure out ways to interface microcontroller with the...
  9. HellasTechn

    RS232 - RS422 CONVERTER

    Because i work on old GPS receivers and compasses that communicate via RS422 while i practice ways to interface them with microcontrollers that use rs232 (either ttl or cmos voltage levels). Though your idea is not that bad. One other alternative i see is for me to build such a converter with...
  10. HellasTechn

    RS232 - RS422 CONVERTER

    HELLO ! I am looking for some converter that can convert rs232 to rs422 and at the same time rs422 back to rs232. In other words i need to connect the converter to my laptops rs232 serial port and exchange data between an rs422 device. Probably something that can be powered from a 5v usb port...
  11. HellasTechn

    Kenwood KA1030 audio amplifier problem

    Yes. but i will triple check just to be sure.
  12. HellasTechn

    Good rosin flux paste brands?

    Anny suggestions for smd soldering ? like the "no residue" style ? The ones i bought on ebay do leave residue no matter if they claim not to.
  13. HellasTechn

    Philips dfr-9000 Blowing fuse

    First thing i would look is the UCD Amplifier board. Under the heatsink there are some power transistors. remove and check them. One or more could have gone short thus blowing your fuse. Though the protection should kick in before it blows the fuse but... Again thats just a guess. P.S. Here is...
  14. HellasTechn

    Kenwood KA1030 audio amplifier problem

    No ideas?
  15. HellasTechn

    RS422 to RS232 converter.

    Back again digging this long dead thread. Like dorke suggested in #30 but a little differently...I pulled the inputs to ground through a 10k resistor. the problem went away and the UA chip works fine ! Is correct to pull the + and - inputs to ground through 10k resistor ? Or should i stick to...
  16. HellasTechn

    Kenwood KA1030 audio amplifier problem

    Good idea. Here they are: Also the picture Mainboard marked shows the location on the circuit of the components i found faulty and replaced.
  17. HellasTechn

    Kenwood KA1030 audio amplifier problem

    Hello again ! The amplifier mentioned in the title was gifted to me by someone who doesnt want to keep it because it is not working. I am thinking to fix it and keep it as spare. When i pluged it in it would not turn on and no LED'd in front panel came on. I opened it and found the mains fuse...
  18. HellasTechn

    Fast Switching Relay for High frequency Signals

    Maybe something like this ? https://www.ebay.com/itm/5x-pcs-TELEDYNE-RELAY-J-412D-26L-DPDT-MILITARY-RELAY-ULTRAMINIATURE/222907086497?hash=item33e64c36a1:g:zyoAAOSwWGxawUNB Though i am not sure if it can take 100V rms.
  19. HellasTechn

    What circuit makes a HIGH by detecting LAST pulse

    The watch-dog timer is different than an lm555 missing pulse detector but in this case both can do the same job. I like the 555 missing pulse detector more :) Plus it requires no programming (not sure about the watch-dog timer) and is so so easy to make.
  20. HellasTechn

    Tektronix 2430a ram chip question

    Neither have i.
Top