Help identifying component

Discussion in 'General Electronics Chat' started by Chuck Whitt, Sep 23, 2015.

  1. Chuck Whitt

    Thread Starter New Member

    Sep 23, 2015
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    I believe this component is a MELF diode, probably a BB215 (based on the information contained in this web site - http://www.marsport.org.uk/smd/sod80.htm). Can anyone verify this for me? I have not dealt with a MELF diode before (never even heard of such a thing before beginning my research). Can any equivalent diode be used as a replacement? rudder_angle_sensor.jpg
     
  2. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    I'm uncertain I understand your question:confused: -- It goes without saying that 'leadless face' devices may be substituted with electrically equivalent devices of disparate geometry -- Provided they are 'mountable' in the applicable equipment...

    Best regards
    HP
     
  3. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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  4. Chuck Whitt

    Thread Starter New Member

    Sep 23, 2015
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    I thought about how dumb that sounded after I posted it - of course, if the electrical characteristics are the same, then it can be substituted. nonetheless, thanks for your response.
     
  5. Chuck Whitt

    Thread Starter New Member

    Sep 23, 2015
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    Thanks, Kermit2, that looks to be what I've been looking for!
     
  6. Chuck Whitt

    Thread Starter New Member

    Sep 23, 2015
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    Can I indulge your favor with more questions? On the board above are two SMD capacitors (lower right). There are no markings on these. How would I go about identifying their values? I've never used a capacitance meter, if that is indeed the answer, would the devices need to be removed from the circuit to get a good reading?
     
  7. ISB123

    Well-Known Member

    May 21, 2014
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    Take a picture of them and tell us the name of 8 pin IC that is one the board.
     
  8. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    Take them out and measure. Or guess, if they are just bypass caps.
     
  9. Chuck Whitt

    Thread Starter New Member

    Sep 23, 2015
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    I'll kill two birds with one stone here. The picture shows one of two ceramic caps (the larger one) above the other circled component. The cap measures (approx) 3.4mm x 2.0mm x 2.0mm. The smaller one measures (approx) 3.3mm x 1.6mm x 0.8mm. The larger cap ties to V+ (pin 8) of the IC on one side, and to the V- (pin 4) on the other side. The smaller cap, in parallel with a 180k resistor, ties to the in (pin 2) and out (pin 1) pins of the opamp.

    The circled device is marked "PJ93 HF" and measures 4.3mm x 2.7mm x 2.4mm. Looking in Blackwell's "The SMD Codebook" (http://www.marsport.org.uk/smd/mainframe.htm), it defines a device with a PJ code as a BB159 a "UHF Varicap 2-11pF" in a SOD-323 package. In the "Marking Codes of Diodes SMD Devices" reference (http://www.instructables.com/files/orig/F7W/GZZ8/HRTWJLRR/F7WGZZ8HRTWJLRR.pdf), it list devices with the PJ code as a DDZ20CS (or variant thereof), a "Precision Zener Diode" in a SOD-323. Digikey's datasheet verifies that this device has a "PJ" marking and is in a SOD-323 package. The problem, besides being defined as two different devices (BB159 and DDZ20CS), is that the dimensions don't match that of a SOD-323 package. So where do I go from here?

    The IC that all of this stuff is based on is a LMC6492 dual op-amp. The purpose of the circuit is to detect movement through the 10k precision linear potentiometer that is the major component of the board.
     
  10. ian field

    Distinguished Member

    Oct 27, 2012
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    Very rarely do ceramic chip capacitors have any markings. You should remove them to get an accurate measurements without the influence of other components.

    The Peak Atlas LCR is a very useable instrument, and you can buy an accessory lead kit that includes tweezer style probes for small SMD parts.

    There are various similar instruments on the market - including ones with the whole instrument built into tweezer probes.
     
  11. Chuck Whitt

    Thread Starter New Member

    Sep 23, 2015
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    Oh yeah, more toys! WooHoo!
    P.S., don't let the wife know. ;-)
     
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