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  1. CDRIVE

    Latching Relays

    Dave, I forgot to mention that if you're hell bent on a partially home brewed hack take a look at this link.. http://www.ebay.com/itm/DC-5V-12V-24V-Infinite-Cycle-Delay-Timing-Timer-Relay-ON-OFF-Switch-Loop-Module-/191909501362 Take note of the push button N/O switch in the product photo of...
  2. CDRIVE

    Latching Relays

    Dave, I'm very sorry for not replying when I said I would. I have a long list of excuses but I'll spare you of the details. Before you spend time and money fabricating a burglar alarm have you searched through Amazon and Ebay? The Chinese have totally changed the electronics market to the...
  3. CDRIVE

    Radio transmitter, options for reducing harmonic emissions

    You are totally misinterpreting the FCC's 100mW regulation. While it permits unlicensed radio transmission it does NOT absolve the unlicensed or even licensed transmission of any interference on any band or any frequency. Chris
  4. CDRIVE

    PIR operated DC motor project odd behaviour help

    Hello Ivan, I'm involved in another topic that involves a timeout period. I then remembered your project utilized a timer module purchased on Ebay which brought me back to this topic. When I followed the Ebay link to your timer module I had an "OH SH!T!" moment because I knew I screwed up...
  5. CDRIVE

    Latching Relays

    I drew that circuit some years ago. It was primarily intended to demonstrate how a relay with spare contacts could be wired to latch. Tomorrow I'll post an updated version with a full explanation. I'll also do my best to answer all your questions. Chris
  6. CDRIVE

    Serial communication problem.

    Since Reverse Active Mode is an inexplicable revelation to this old dog too, I thought some sandbox time was is order. Here's some (DC Analysis) spice plots on a generic NPN. Enjoy. Chris
  7. CDRIVE

    Induction Heater Diy, How To Improve Performance?

    I'm curious. As per the link that Kelly gave you what value inductance does your coil calculate to? Also, what's the value of the parallel Cap? Chris
  8. CDRIVE

    Latching Relays

    Here's a simple (Closed Loop Alarm) latch using a DPDT relay. Chris
  9. CDRIVE

    Serial communication problem.

    Harald, that's an issue that I never questioned him about because I assumed he was scoping the base signal at the input end of the base resistor, as you surmised. That said I really do appreciate your expertise. Particularly regarding Bipolar Reverse Mode Of Operation. I'm learning about this...
  10. CDRIVE

    Serial communication problem.

    Here's some plots with an inverted NPN that explain a lot. Chris
  11. CDRIVE

    Serial communication problem.

    Constantine, I've done some simulations since my last post. I believe that later today I can clearly explain the scope readings you're experiencing. Right now I'm long overdue for a haircut. Chris
  12. CDRIVE

    Op Amp with a/c output

    These questions have not been answered. Until they are this thread is going to be tantamount to a fishing expedition. Chris
  13. CDRIVE

    I'm trying to rig a bike horn to an alarm clock

    Alexander, just a quick note. Though I specified Q1 as a 2N3904 it's not a critical component value. A 2N2222 will also work just fine. In fact just about any small signal NPN will do the job in this undemanding application. Chris
  14. CDRIVE

    Serial communication problem.

    We have quite a few EE's here that posses a far greater understanding of the physics involved with bipolar transistors than I do. Hopefully one of them will give you a precise and detailed explanation. I can tell you two things though. (1) If you reduce R2 to 100Ω you will see very different...
  15. CDRIVE

    I'm trying to rig a bike horn to an alarm clock

    Done. ;) Cheers Chris
  16. CDRIVE

    Serial communication problem.

    Is there a reason that you have ch1 and ch2 overlapping each other? Please separate the baseline traces so they're not overlapping each other. It's also good practice to assign Ch1 to the Input and Ch2 to the Output. Chris
  17. CDRIVE

    I'm trying to rig a bike horn to an alarm clock

    Here's a schematic of Duke's and Alec's suggestion. Chris
  18. CDRIVE

    Serial communication problem.

    I keep thinking that Rod Serling is hiding in the shadows! Is your scope a dual trace? If so please post the input signal vs the output signal. Chris
  19. CDRIVE

    I'm trying to rig a bike horn to an alarm clock

    Yeah, "Distructables" gives just enough bad information to help a nube electrocute themselves or burn their house down! Chris
  20. CDRIVE

    I'm trying to rig a bike horn to an alarm clock

    In addition to the advice already given ... If your motor bike horn is of the electromagnetic variety you may also want to install a protection diode across it. Chris
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