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  1. hevans1944

    questions anode crt

    Everything dies... eventually. Just be aware that scratching the glass envelope of a CRT does nothing to prolong the process, and it may tend to speed things up if the CRT is handled carelessly. And, no, you cannot recover from scratching. I owned a large color TV in the 1960s that developed a...
  2. hevans1944

    questions anode crt

    You should not be messing with the anode cap unless you have experience with this. The CRT acts as a large capacitor that can retain a high voltage for several days unless it is discharged. The anode cap is often difficult to remove after being in place for years, exposed to ozone and other...
  3. hevans1944

    Oscilloscope identification and evaluation?

    Oops! 'Scope I purchased was the DSO5202P instead of the DSO5202B. The B version has more memory depth, but I found the P version to be more than adequate.
  4. hevans1944

    Help needed for transmitting 15V signal to 10 metres at 8KB/s using RS232 or RS422 cable

    @Prakash123: Methinks you don't have a clue about what you are doing, or attempting to do. Why are you using a POWER mosfet as a data transmitter? The diagrams you uploaded are BLOCK diagrams, NOT schematic diagrams. A schematic diagram shows ALL the terminal connections between each and every...
  5. hevans1944

    Oscilloscope identification and evaluation?

    I bought a Hantek DSO5202B in 2016, just prior to moving to Florida, from Circuits Specialists. I don't remember what I paid for it then, but it lists for $319.00 today with free shipping to any of the United States from Tempe AZ. It isn't a barn burner, with just two channels of 200 MHz...
  6. hevans1944

    Oscilloscope identification and evaluation?

    It appears to be a Japanese copy of a Tektronix analog CRO (cathode ray oscilloscope) from the 20th Century, but at not a particularly good price considering that it is used, repair parts may be difficult or impossible to obtain, and shipping cost is a huge chunk of the purchase price. I know...
  7. hevans1944

    BCD to 7 segment display

    That's probably true, but given that there has been no reply, no dialog established, nor any further questions asked by the op, I would flag this as a "drive-by" poster who is not interested in learning how to read a datasheet but just wants someone to provide a quick and painless answer to...
  8. hevans1944

    “Simple” volt/amp question

    If I understand the Simplisafe design philosophy, they just want to make it "easy" to install a video-equipped "doorbell" using existing doorbell wiring to obtain power for the video. Good luck with that. Should work if you know what you are doing...
  9. hevans1944

    “Simple” volt/amp question

    Any way you go, you will have to install a pair of insulated, small-gauge, "doorbell wires" between your Simplisafe device and an external, low-voltage transformer. Wherever the transformer is installed, you need to also install a current-limiting resistor OR a traditional electro-mechanical...
  10. hevans1944

    “Simple” volt/amp question

    Probably not. Where are you getting "the hot" lead from? If this comes from a low-voltage AC transformer, the "usual" procedure when connecting a doorbell (or chime) is to wire the power supply "hot" and "common" to the doorbell through a normally-open push-button switch. Pressing the switch...
  11. hevans1944

    BCD to 7 segment display

    Oops! I didn't notice this question was in the Homework Forum. My bad. The reply that @Harald Kapp made in his post #2 says all that needs to be said. I will ask no more "trick" questions. Moderator, please close this thread.
  12. hevans1944

    Help needed for transmitting 15V signal to 10 metres at 8KB/s using RS232 or RS422 cable

    Where did you get the idea that RS232 or RS422 standards specify a nine-pin DB9 connector and nine-wire cable? And why do you want to waste seven data lines to transmit data at such a slow rate as 8000 bits per second? And why do you think that supplying power (+15V & 0V) over the wiring between...
  13. hevans1944

    BCD to 7 segment display

    Oh, really? And for what, pray tell, is the fourth input pin being used? [Mod edit: answer deleted - homework!]
  14. hevans1944

    6v LED brighter with 3v battery

    You should compare this datasheet for CR2016 with this datasheet for the CR2032 to gain some insight into what is going on. BTW, neither cell was designed to power the relatively high current demands (20 mA and up) of LEDs. The fact that they will work in that application simply lines the...
  15. hevans1944

    Charging AA Li-ion batteries

    Oops! It appears both ratings, mWh and mAh, are used to specify battery capacity. My bad. However, the two measurements DO NOT measure the same thing, so you cannot directly compare a mWh rating with a mAh rating. Google "mWh vs mAh" for more information.
  16. hevans1944

    Charging AA Li-ion batteries

    I think these contain regular 3.7 V Li-ion cells and a buck-converter to reduce the voltage to 1.5 V. Charging from a 5 V USB port would still require some sort of charge-regulating hardware and/or software. And they are a little pricey compared to 1.2 V NiMH cells, but they surely look to be...
  17. hevans1944

    novelty led blinker, how is it done?

    I used to have dreams of flying (without using an airplane!), but they have become rare lately. I was referring to so-called "out-of-body" experiences, which AFAIK I have never had, that occur typically while unconscious on an operating table. I can't imagine how that can even occur, given that...
  18. hevans1944

    Charging AA Li-ion batteries

    Your statement doesn't make sense. Firstly, as @BobK pointed out, lithium ion cells are NOT 1.5 V. You may be thinking of alkaline cells, which DO have a typical open-circuit terminal voltage of 1.5 V. Unfortunately, alkaline cells are NOT rechargeable. Secondly, you may be thinking that you...
  19. hevans1944

    novelty led blinker, how is it done?

    I just now Googled "septic shock blood poisoning" and discovered there is a sixty percent death rate, probably because of a late diagnosis. You are indeed fortunate to have doctors who recognized your condition and treated it in time. My "medical problems" seem picayune compared to the...
  20. hevans1944

    novelty led blinker, how is it done?

    I would like to think that I will be around for the next 20 or 30 years, but realistically that probably won't happen. There are too many co-morbidity factors to go along with my failing heart to survive all of them. In the mean time, I will just live one day at a time and try to be grateful for...
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