POT Problem

[bsnut]

Jon,

I was testing my muli-mode selector switch with the POT comand and the first test work prefectly with Prop1 and a meter. When I added the Cds cell, I used a volt-meter to test rest of the circuit it worked fine, until I reconnected the RC servo cable in revrese on Prop1 pins (cable "W" connected to the prop1 "B") and I power-up it caused the Prop1 to shut down. The Prop1 and power supplies started to work again and was able to download to it again. I retest the same test, but checked to make sure the colors on the RC servo cable matched the pin out on the Prop1 and it still shuts down with uln2803 removed this time.

The question is what did I damaged or did I damage any thing.   

Note: I was working solderless prototyping board.

[JonnyMac]

I don't why your Prop-1 shut down.  With a properly-constructed POT circuit (which is a series RC) it should work even if the cable is backward, and I verified this with a Prop-Pot.  I think you've got something else going on with your external circuit.  Can you post a schematic?

[bsnut]

Jon,

I would post a schematic, but I do not have the schematic software. I know it is easier to see schematic. 

I understand what you are saying, it doesn't matter if you connected the RC servo cable on the pins backwards. The way I wired it first, was to the way the Basic Stamp Manual shows. Then I changed the setup and connected 3- 10Kohm resistors in series with the 0.1uF cap to ground, and then I, connected one N.O. pushbutton between the 0.1uF cap and the last resistor and the other side of the pushbutton between first and second resistor, and second N.O. pushbutton between the 0.1uF cap and the last resistor and the other side of the pushbutton between the second and the last resistor. This setup worked fine when ran I, it the first time using the code below without the Cds cell across the last resistor. Then I, added the Cds cell across the last resistor at a later date.  Then I had downloaded different test program to the Prop1 before returning back to this setup which I didn't download the test code below before connecting the RC servo cable, I didn't think it mater. The only thing I, can think I did wrong was, when I reconnected the Programming Adapter to the Prop1 for Debugging and downloading, I must connected it wrong, but what I don't understand is, I was able to download the same code below to the Prop1 later on after the prop1 shut down.  I did have a prototyping wire that I was using for voltmeter testing between the 0.1uF cap and the last resistor that could of touch the other side of the cap(shorting the cap) or touch the +5VDC when I was reconnecting the RC servo cable back to the Prop1. The Cds cell was across the last resistor when the Prop1 shut down the first time. Cds cell with LED is homemade analog optisolator which will be used for voltage detection for the Solar Battery Charger Controller that I'm building is shielded in black heat shrink. I tried the same setup, but removed the wire I was testing with and still shut down. What do you think what happen?  ???

I will try the setup from the topic "Selector Switch/POT command" using the homemade analog optisolator that made and the same test code below, but change to a different O/I Pin.

Note: This code is from the Basic Stamp Manual and I changed "PotPin" from 0 to 6.

' POT.BS1
' This program demonstrates the use of the POT command.  Connect one side
' of a 10K potiometer to P0.  To the other side of the potentiometer
' connect a 0.1 uF capacitor, and then connect the second side of the
' capacitor to Vss (ground).  Before running demo program, use the
' Run | POT Scaling dialog to determine the best Scale factor.

' {$STAMP BS1}
' {$PBASIC 1.0}

SYMBOL  PotPin          = 6             ' 10K pot connected to P6 and Setup jumper removed
SYMBOL  Scale           = 110           ' scale value for test circuit

SYMBOL  level           = B2            ' storage of pot "level"

Main:
  POT PotPin, Scale, level              ' read pot level
  DEBUG CLS, "Level = ", #level         ' display
  PAUSE 50                              ' short delay
  GOTO Main                             ' repeat forever
  END

Thanks,
William "bsnut"

[JonnyMac]

You said you changed to a different pin.  Is the ULN attached to that pin? -- it will affect the POT function. 

BTW, you can download ExpressPCB at no charge; that's the program I use for posting schematics in the forums.  I also use it for creating prototype PCBs.

[bsnut]

To answer the first question. ULN was connected in its socket on that pin. I also removed ULN it from its socket the last time. I will double check my code today.

Thanks for the link to ExpressPCB, I just download  this morning and will post a schematic for you later this week.

[bsnut]

Jon,
I know one week turned into three months ;D, but I am busy like you. Working between my nonprofit groups the Baltimore Streetcar Museum (Trolleycars) and the Zuni Maritime Foundation (Working on the ship, the one that was in the Perfect Storm).
I was having problems posting the schematic on this site. One problem is I, couldn't convert to file types for this site because ExpressPCB only converts Bit Map only. I converted file to GIF and I couldn't open it to see if it worked (look at it). Is their a way I can send you copy of my schematic so it can get posted in this topic. I hope my one week doesn't take three months or more ;D

[JonnyMac]

I use a somewhat involved process to get schematics out of ExpressPCB for Internet posting.  If you've converted to bitmap and have a graphics program you can open the BMP, crop away the unnecessary stuff and then save as a JPG or PNG.  You can send the file to my regular email if you have trouble and I'll do it for you (though I can't do this stuff for everyone, especially this time of year).

[bsnut]

Jon,
I was able to get the pot problem fixed and working in app fine and wasn't the code  8).You were right, the problem was the ULN still connected in its socket on pin7 and no more problems after that. :o As, I say you learn by doing and making mistakes. One thing I, can say about the Prop-1 and the Stamps is like a Timex watch ;D "It takes a licking and keeps on ticking" mayby not the ULN sometimes.

Thanks for the support you offer on this site. I post pictures later on when I finish this project.