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  1. CDRIVE

    GPS NMEA, Failover Circuit upgrade attempt.

    Looking back, once again, I see that the Serial Out (B.0) which is also a reserved programming pin is being used too! Why? There are plenty of unused pins you can use. Pins associated with programming the chip should be avoided unless the developer has no other choice. Chris
  2. CDRIVE

    GPS NMEA, Failover Circuit upgrade attempt.

    Much earlier in this thread I think I mentioned caveats involved when using the program download (Serial In) pin for anything other than actually programming the chip. I suggest reading up on the "Disconnect" and "Reconnect" commands found in Picaxe_Manual2 (Basic Commands); when using C.5 for...
  3. CDRIVE

    GPS NMEA, Failover Circuit upgrade attempt.

    Never mind it was brain fart. You asked Sadler about the "hserin" command and he replied with an explanation of it. Somehow hserin got embedded in my old brain but it has no relevance your project. I opened one of Sadler's text files that contained code he wrote for you. He's using the "serin"...
  4. CDRIVE

    GPS NMEA, Failover Circuit upgrade attempt.

    I thought that I read (within this topic) that "hserin" is the command being used. Am I wrong? Chris
  5. CDRIVE

    GPS NMEA, Failover Circuit upgrade attempt.

    This is a long thread so it's possible that I may have missed something, though I did go back and read from page 1 on. I must admit that I'm a bit confused. I believe I read that you're using the "hserin" command on C5 and B0 but as far as I can ascertain B1 is only pin available for that...
  6. CDRIVE

    GPS NMEA, Failover Circuit upgrade attempt.

    Roger that Constantine. It's my error. The diode is needed and its polarity is correct. Chris
  7. CDRIVE

    GPS NMEA, Failover Circuit upgrade attempt.

    Constantine, I forgot to mention that the Diode connected to the 7805 output pin is backward. For that matter, what's its purpose? I see no need for it. While we're on the subject of schematics here's a tip. Always include component ID numbers IE; R1, C1, C2, D2, etc, when you draw a schematic...
  8. CDRIVE

    GPS NMEA, Failover Circuit upgrade attempt.

    Actually, Picaxe I/0 pins contain two Diodes. One Diode is as Sadler pointed out and the other is connected with its Cathode = Pin and Anode = (Vss) GND. It's incorporated to protect the input from Negative voltages like you'd find from RS232 Serial Port data and control pin levels. With regard...
  9. CDRIVE

    Need advise - Screwed up on my PCB - Need replacement part

    Ah, that's the best part of working with μC's. Changing logic via code is soooo easy! Chris
  10. CDRIVE

    Need advise - Screwed up on my PCB - Need replacement part

    You do realize that the M54580P's input logic is opposite of the ULN series? The ULN's Collector (output) goes low when the input goes high. The M54580P's Collector (output) goes high when the input goes low. Chris
  11. CDRIVE

    switching a relay - but on second switch. ( if that makes sense? )

    This purely curiosity... What is the purpose of this mechanism? Chris
  12. CDRIVE

    Two Compressors, One Pump

    This circuit will run the pump when either or both compressors are running. D1 & D2 are Diode Isolators. They're very common and inexpensive. The other Diodes are Back EMF Diodes. They should be integral to the relays and are shown enclosed in a box. In other words, they already exist (OEM)...
  13. CDRIVE

    Two Compressors, One Pump

    Chainplate, I forgot to ask you if the compressors were originally wired in an "OR" or an "AND" logic configuration? Restated, was this circuit configured to insure that both compressors would not be on simultaneously (OR) or did both compressors sometimes run at the same time (AND) if either...
  14. CDRIVE

    Two Compressors, One Pump

    Are you saying that the boxed parts returned to you by that turkey only included 2 relays but the system originally had 3 when he removed the compressors? BTW, I want you to know that if I were a Judge adjudicating that turkey I would award you pain & suffering. This would be on the grounds...
  15. CDRIVE

    Current Amplification

    My guess is that your instructor requires that the circuit be capable of functioning over an audio frequency spectrum that can be changed via the signal generator. It's either that or your instructor is also expecting you to build a variable frequency signal source but I doubt it. I would also...
  16. CDRIVE

    Transformers

    Well, it's quite fortunate for you that somehow you found your way to EP. Where elitists snobs are not celebrated. ;) Chris
  17. CDRIVE

    Transformers

    While two or more transformers may have the same input/output voltage rating, or better stated "Turns Ratio", they can have totally different current ratings. Basically the larger the wire gauge the higher the current rating. This in turn dictates a larger transformer core. You're understanding...
  18. CDRIVE

    Old multimeter

    Yeah, many of them were damaged on the "Current" functions too! Bent movement vanes was another glaring indication of abuse. Chris
  19. CDRIVE

    Wives Say The Damnedest Things!

    So my wife buys a new plastic shower curtain that employs embedded magnets to hold it snug to the tub. She takes a shower and tells me she thinks she put it up backward because the magnets aren't holding it firmly to the tub. Sure enough when I take a shower I see these weak little suckers don't...
  20. CDRIVE

    Home Depot fail

    Actually HD should be congratulated for their ability to supply 'Artisan Lumber' at construction lumber prices. After all, Artisan's who create oddly shaped objects get a real time saver with HD lumber.... It's sold 'Pre - Warped'! I marvel at all those the graceful bows, cups and twists. The...
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