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Using OEM parts in my design — Parallax Forums

Using OEM parts in my design

dufflingduffling Posts: 73
edited 2005-03-23 08:50 in BASIC Stamp
Im now happy with my design and wish to make 5-10 units ..

i understand i can purchase OEM parts , interp chip , resonator , eeprom to save costs.

my question is .. is the voltage reg IC 100% nessicary ? does this ensure the stamp is not damaged by too much current on the pins?

the other components i assume can be replaced with normal sized components , transistors and resistors ..

thanks in advance.
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Comments

  • BeanBean Posts: 8,129
    edited 2005-03-22 12:15
    I would think if you already have a REGULATED +5vdc supply, you can get by without it.
    But make sure the ic's are properly bypassed with capacitors.
    Bean.

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  • ForrestForrest Posts: 1,341
    edited 2005-03-22 12:21
    The OEM BS2 and BS2SX use a thru hole LM2940-5 volt regulator (TO-220 package). See here for more info www.parallax.com/html_pages/products/basicstamps/basic_stamps_oem.asp
  • GadgetmanGadgetman Posts: 2,436
    edited 2005-03-22 12:25
    You will need some sort of voltage regulator, unless you have a fixed and stable 5V input of some sort already. You don't necessarily need to use the one used on the BS2, though, a 7805 will do just fine.

    There's another chip, though, which resets the Interpreter if the voltage drops too low. I can't see it in the OEM kits, but it is mounted on the ordinary modules. If you're working with a battery-powered system, one of those would be nice, as there's no telling what the BS2 will do if the voltage drops too far. (I suggest checking the tolerances for the Interpreter, EEPROM and whatever else you're using to see what they're OK with, but I think a 4.2V chip is used on the BS1)
  • Steve JoblinSteve Joblin Posts: 784
    edited 2005-03-22 18:36
    You could streamline your design by "separating" the Serial connection part from the actual stamp part. By this, I mean that you could create the serial port and associated transistors, resistors, etc. on a "Programmer board" and just the "Interpreter" , EEPROM, and resonator on your board. then connect the two via a 4 Pin header. This will reduce your cost by only having to buy the Serial portion of the components only once. Each project board would cost $18.38 for a Stamp 2 (Resonator = $2.38, EEPROM $5.00, Interpreter Chip $11.00).

    NOTE - MY APPOLOLOGIES TO PARALLAX FOR OFFERING CUSTOMERS A LESS EXPENSIVE ALTERNATIVE... I AM A HUGE FAN AND KNOW THAT THE COMPANY CAN ONLY GROW AND GET BETTER BASED ON REVENUES, WHICH MY SOLUTION IS REDUCING. SORRY!
  • allanlane5allanlane5 Posts: 3,815
    edited 2005-03-22 19:20
    Yes, the on-module (or on OEM Board) regulator (either 2940-5 low-drop-out, or the 7805) is there to provide +5 volts for the PIC chip and the EEPROM. Really, all you need to run the BS2 is the PIC chip, the resonator, and the EEPROM.

    However, you will need to get +5 volts from somewhere -- but if you already have your own power supply providing +5, then you don't need the regulator to do it again.

    Now, if you want to program the BS2 in-circuit, you'll also need the transistors for the programming port, and the reset circuit. Steve's idea of using a 4-pin jumper to connect a removable programming pigtail is a good one.
  • dufflingduffling Posts: 73
    edited 2005-03-23 06:58
    Ok . now the IC mounted on My BS2SX is labelled LT 228 , I Searched for this part and it said it was a voltage regulator in addition to the LM2940 On the BOE

    is this part nessicary ? is this also the part that protects against brownouts?
  • dufflingduffling Posts: 73
    edited 2005-03-23 07:10
    Does anyone have any slightly more simplified circuit schematics for the BS2SX + serial circuits?

    ive looked at the PDF showing the layout on the actual stamp but if anyone has another layout i could study this would be great!
  • GadgetmanGadgetman Posts: 2,436
    edited 2005-03-23 08:50
    duffling said...
    Ok . now the IC mounted on My BS2SX is labelled LT 228 , I Searched for this part and it said it was a voltage regulator in addition to the LM2940 On the BOE

    is this part nessicary ? is this also the part that protects against brownouts?
    The LT228 isn't used when the BS2SX is mounted in the BOE as it gets its 5V from the LM2940.
    It is only used when you feed the BS2SX power from another source, like a 9V battery.

    No, it doesn't provide brownout protection.
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