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Type: Posts; User: JDW_

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  1. Closed: Re: How to use the same RELAY on 12V & 24V vehicles

    I intend to use a small dual-switch signal relay to break two signal wires coming from the PUSH start button in modern cars. The current relay I have handles a max of 2A, but even that’s overkill...
  2. Closed: Re: How to use the same RELAY on 12V & 24V vehicles

    Thank you for the tip.

    I actually posted this same question in another forum today so I could get a lot of ideas at once. A suggestion made there was that I should consider using PWM on the...
  3. Closed: Re: How to use the same RELAY on 12V & 24V vehicles

    Shunting all that current (24V down to 12V) through a Zener is perhaps not the best approach. But you are correct about 3.3V relays being available. It's just that they typically only carry 250mA,...
  4. Closed: How to use the same RELAY on 12V & 24V vehicles

    I designed a circuit that operates on both 12V or 24V vehicles (my 150mA-max output voltage regulator steps 12V or 24V down to 3.3V for an MCU and other digital circuitry). I also need a relay on...
  5. Closed: Re: SMD Electrolytic Capacitor: Decoding Capacitance & Voltage Rating

    The lowest cost SMD ceramic XR7 cap at Mouser that is suitable for my application, in the <10pc quantities I need, is US$0.85EA and 20% tolerance, and drops 30% in capacitance with applied 5V bias...
  6. Closed: Re: SMD Electrolytic Capacitor: Decoding Capacitance & Voltage Rating

    The problem with ceramic capacitors is that they lose capacitance sharply with applied bias voltage. Many datasheets are completely ridiculous in that they don’t even supply me with a curve to see...
  7. Closed: Re: SMD Electrolytic Capacitor: Decoding Capacitance & Voltage Rating

    In reply to your question, as I said in my previous post, the reason I have been thinking about Tantalum or even Niobium Oxide capacitors is because even the best electrolytic capacitors will leak at...
  8. Closed: Re: SMD Electrolytic Capacitor: Decoding Capacitance & Voltage Rating

    Thank you for sharing your thoughts.

    I'm pretty sure they are 6.3v rated in light of their size and in light of the fact their (+) side connects to the 5V rail. I now need to ponder suitable...
  9. Closed: SMD Electrolytic Capacitor: Decoding Capacitance & Voltage Rating

    I have an old accelerator board used in the PDS slot of an Apple Macintosh SE/30. The board was manufactured around 1994. I want to replace the electrolytic capacitors but I'm not sure how to...
  10. [PIC]Closed: Re: Using a PIC to generate square wave sweep tones (audio)

    I wrote the ASM code below and tested it in-circuit with H-BRIDGE and 8-ohm speaker. The code doesn't include a tonal sweep. This code is simply to test a simple duo-tone sequence of 625Hz for...
  11. [PIC]Closed: Re: Using a PIC to generate square wave sweep tones (audio)

    Thank you for your reply, Brian.

    I have an old WinXP PC that runs MPLAB 8.92 and MPASM 5.51 wonderfully, but it's too old to even upgrade to Win7. I installed MPLAB X 3.05 quite a long time ago,...
  12. [PIC]Closed: Re: Using a PIC to generate square wave sweep tones (audio)

    Brian, I simply don't have a PICKIT3. Instead, I use a PM3 programmer. So what I was saying is that I don't have an in-circuit debugger.

    Heading off on a tangent depends on who you ask. I only...
  13. [PIC]Closed: Re: Using a PIC to generate square wave sweep tones (audio)

    FvM,

    Thank you for your reply.

    I actually posted about my project in the Microchip forums (a horribly buggy forum, by the way), and also on PICLIST. Despite my having posted actual ASM code,...
  14. [PIC]Closed: Re: Using a PIC to generate square wave sweep tones (audio)

    I am using a PIC to generate tones that will be outputted via H-BRIDGE to an 8-ohm speaker. An H-BRIDGE requires 2 complementary (180° out of phase) outputs to be fed into it. The CWG module of the...
  15. [PIC]Closed: Re: Using a PIC to generate square wave sweep tones (audio)

    I'm a bit confused by the CWG setup on the PIC16F150x-series. The datasheet gives a very specific sequence that should be followed, but I discovered that the C-code generated by the MPLAB Code...
  16. [PIC]Closed: Re: Using a PIC to generate square wave sweep tones (audio)

    I started learning PICs back in 1996. I had the 2-inch thick Embedded Control Handbook dated 1994/1995 at the time. How did I learn? By reading through all that example code. Some folks are...
  17. [PIC]Closed: Re: Using a PIC to generate square wave sweep tones (audio)

    Conceptually, I somewhat follow you, but do you have an assembly code example? I have Googled for days and can't find even a single example of PIC Assembly accomplishing that. Lots of people talk...
  18. [PIC]Closed: Re: Using a PIC to generate square wave sweep tones (audio)

    Gentlemen,

    Thank you for the replies.

    First, please understand I do not need anything fancy. I am not trying to reproduce a SIN wave. I only need a square wave output. Why? Because I only...
  19. [PIC]Closed: Using a PIC to generate square wave sweep tones (audio)

    First some background. I began learning PIC assembly programming in the 1990s, self-taught from Microchips documents. I have various PICs, a PM3 programmer, and still use MPLAB 8.x. I do not know...
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