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  1. hevans1944

    Laser Diode Project. Help!

    Right! That's why the OP should measure the current drawn by one of them before trying to power up 100. I missed that, so thanks @BobK for pointing it out. Also, these diodes were apparently originally used in a laser printer where they were out of sight. 5 mW output power in the visible is...
  2. hevans1944

    voltage and current amplifier

    Sure, there are amplifiers that are specifically called "power amplifiers" because they accept a "low power" signal input and produce a "high power" signal output. In the RF field, where input impedance is commonly the same as output impedance, the power amplifier amplification factor, or gain...
  3. hevans1944

    Direction, Rotation and Memory project

    @Hellmut1956: You are right of course. We all had to take baby steps when we began this journey. I don't think I would have stepped off into the deep end of the pool, so to speak, with such an ambitious project as this one appears to be. But, OTOH, we didn't have as many tools, or prior...
  4. hevans1944

    RC Toy Car

    I don't know where the OP lives, but if there is a Radio Shack nearby they may be able to cut you a deal on toy RC cars. All but three RS stores are now closed in the Dayton OH area. The three that remain open appear to have a glut of cell phones and RC toys. There might be some bargains to be...
  5. hevans1944

    Laser Diode Project. Help!

    You should not try to connect laser diodes in parallel, unless each diode contains a current driver integrated into the laser diode package. This could be something as simple as a current-limiting resistor. And that does appear to be the case for cheap Chinese knock-off laser diodes, such as the...
  6. hevans1944

    Direction, Rotation and Memory project

    Is this the hardware you are trying to use? What microprocessor will you use to interface to the TFT Color LCD touch screen? How will you physically make the connections between the TFT LCD touch screen and the microprocessor? Have you downloaded and read the datasheets for the devices you will...
  7. hevans1944

    I'm new to Logic gates and digital electronics and could use some help please!

    I learned on TTL but didn't think this was used much today. If you can get your hands on this logic family, it is a little more forgiving than CMOS. With any logic family, it is always a good idea to either connect unused inputs to ground, or pull them to logic 1 level using a resistor between...
  8. hevans1944

    RC Toy Car

    Lessee... you went from six 1.5 V AA cells providing 9 V DC to a NiCd battery providing 12 V DC? And you might be wondering if that was too much voltage, yes? Yes, it was too much voltage. Did you try to charge the NiCd without disconnecting it from the toy car? A NiCd charger will provide more...
  9. hevans1944

    EP Newsletter

    I got one too. Haven't had much of an opportunity to look at it yet.
  10. hevans1944

    Video surveillance

    200 feet might be a bit of a stretch without some intense IR illumination. Most cameras respond to near IR around 900 nm wavelength. Light-intensified cameras operating in the visible can easily do this without illumination, i.e., so-called starlight scopes, but they are rather pricey and would...
  11. hevans1944

    Need to find a way to do different functions basedon incoming voltage

    I was telepathologically involved with nuclear weapons in 1947 when the transistor was invented, having inspired the development of the atomic bomb three years previously while still in the womb, an attempt to free my father from a German POW camp. Fortunately for Dad, George Patton's Third Army...
  12. hevans1944

    Sanyo Clock radio repair

    Regular contact cleaner does lubricate. It contains both a solvent and a lubricant. Do not use any kind of silicone lubricant on electronics moving parts, such as your slide potentiometer. The silicone residue is a non-conductor that IMO adds nothing. You probably cannot purchase a new clock...
  13. hevans1944

    How to move up/down the frequency wavelength

    And maybe a good physics text too. Is Halliday and Resnik "Fundamentals of Physics" still in print? That's what I started with many moons ago. Edit: Yes it is! Many links available here.
  14. hevans1944

    Need to find a way to do different functions basedon incoming voltage

    Well, your decision then. Reliability should always be the first concern. I have seen too many circuits that "almost" work "most" of the time. I've not seen any relays with 24 V DC coils that pull-in at 12 V DC, but plenty will stay pulled in at that voltage or lower, which could cause a...
  15. hevans1944

    Need to find a way to do different functions basedon incoming voltage

    Ummm. How does the circuit turn off the red LED when 24 V is present?
  16. hevans1944

    How to move up/down the frequency wavelength

    If you already have a waveform from your whatever... a software oscillator? What is that? How is it like a music synthesizer? Do you want to make it play faster/slower? What does AM or FM have to do with anything? What does a log potentiometer have to do with anything? Let's say you have a...
  17. hevans1944

    Drilling pcbs

    You don't need a LARGE drill press. Watch the video uploaded by @Laplace. Tungsten carbide drills are expensive, ranging in price from slightly less than five dollars each to about seven dollars each, depending on length and diameter. Get at least five of each size hole you need to drill, more...
  18. hevans1944

    I'm new to Logic gates and digital electronics and could use some help please!

    May we assume that you can "use" the logic elements more than once to create a digital "circuit" for your emulations? Regardless, what you need is a four-stage binary ripple counter to count from 0000, 0001, 0010, 0011, 0100, 0101, 0110, 0111, 1000 which when applied to the binary coded inputs...
  19. hevans1944

    Drilling pcbs

    Thanks for the video. I guess a good "drill press" for a Dremel-like tool isn't all that hard to cobble together. Maybe I will have another look at the "drill press" attachment that I have for my Dremel Moto-tool.
  20. hevans1944

    Drilling pcbs

    The key is to eliminate wobble and run-out. Never try to drill with a tungsten carbide bit that is spun up in a hand-held drill. Guaranteed to break, usually immediately. The usual drill press attachment for a Dremel tool is a piece of crap, but better than trying to hold the Dremel tool in your...
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