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Squawk Box

Discussion in 'General Electronics Discussion' started by bigkim100, May 4, 2018.

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  1. bigkim100

    bigkim100

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    Apr 17, 2013
    I have a little "SQUAWK BOX" in a toy from the 70's. Its supposed to make R2D2 type noises, and does, the only thing is that the volume is really low. Battery is ok, speaker is ok, so what should I be looking for. Yes it has NO ICs, just regular analogue components.
    Any ideas???
    Thanks in advance
     
  2. kellys_eye

    kellys_eye

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    Jun 25, 2010
    How did you check the battery and speaker?
     
  3. AnalogKid

    AnalogKid

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    718
    Jun 10, 2015
    Is the volume significantly lower than it was in the 70's, or has it decreased recently?

    Photo of the innards?

    ak
     
  4. 73's de Edd

    73's de Edd

    3,085
    1,302
    Aug 21, 2015
    Sir bigkim100 . . . .


    Why is it? . . . . .somehow I think that the associative electronics of that unit . . .is absolutely being no more sophisticated that the build being within a talking / musical greeting card.

    You just need to add in a progressively more appropriately powerful audio amplifier and speaker to its audio output from the chip sound generator proper. . . . which is probably being disguised from you, in being within a mini black plastic blob within a Chip On Board configuration.


    upload_2018-5-4_20-48-49.png


    73's de Edd
    .....
     

    Attached Files:

  5. bigkim100

    bigkim100

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    Apr 17, 2013
    Its speaker is ok, battery ok, altho its speaker is a paper cone unit that is only 2 inch
    hes wide. It has a few old transistors, no COB. It has decreased in sound quite a bit since the 70's, which indicates its something that can dry out, and age, like a electro capacitor. I have pictures of it that Ill post tomorrow, of course I have them on my computer at work.
     
  6. bigkim100

    bigkim100

    84
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    Apr 17, 2013
    Its speaker is ok, battery ok, altho its speaker is a paper cone unit that is only 2 inch
    hes wide. It has a few old transistors, no COB. It has decreased in sound quite a bit since the 70's, which indicates its something that can dry out, and age, like a electro capacitor. I have pictures of it that Ill post tomorrow, of course I have them on my computer at work.
    It actually has a tiny transformer that drives the speaker.
    If I have to, I guess I can add a amplifier, but I have to be careful that tiny 8 ohm speaker may be blasted to shreds, and Ill be picking pieces of black paper cone outta my hair. Any idea on a super simple, fairly low power 9v amp that maybe I could drive from the circuit prior to the transformer??
     
  7. kellys_eye

    kellys_eye

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    Jun 25, 2010
    You can't create the noises you suggest it makes without something more sophisticated than a few old transistors......

    Something is missing from the equation.
     
  8. Audioguru

    Audioguru

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    Sep 24, 2016
    Since the squawk box has an output transformer then it must be from the fifties. Its circuit uses either vacuum tubes or germanium transistors. An LM386 power amplifier IC has an output of 0.45W into 8 ohms (without a transformer) when it is powered by 9V. Here is a Philips audio amplifier from 1955 that uses germanium transistors and an output transformer:
     

    Attached Files:

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  9. bigkim100

    bigkim100

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    Apr 17, 2013
    Wait until tomorrow, I will post pics, but honestly, its just a few resistors 3 Geraniun Transistors, and a output transformers to make a happy set of beeps and boops
     
  10. bigkim100

    bigkim100

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    Apr 17, 2013
    I dont think COBS were around in the 70.s
     
  11. bigkim100

    bigkim100

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    Apr 17, 2013
    Its a fresh 9v from the pack, and I ran the output of my computer to the speaker, and played some music...sounded like what a 2 inch speaker should sound like.
     
  12. 73's de Edd

    73's de Edd

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    Aug 21, 2015
    Sir bigkim100 . . . .

    I hurriedly read right past that initial '70's .

    Seems like a minimum of two transistors would be needed for just the audio amplifier . . . . but the whole system might be based upon a + feedback loop to make the unit into a power oscillator, then the different switched RC components in that loop would create the completely different tones.
    With a few more transistors they could create a critically damped Twin-T oscillator circuit, which, when triggered, could create ringing tones or tapering off tones.
    Give good close ups of both sides of the Pee Cee Bee . . . . .circuitry layout.

    73's de Edd
    .....
     
  13. bigkim100

    bigkim100

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    Apr 17, 2013
    r2d2.jpg
    Tah Dah, you can see the squeeker speaker below, the circuitry to the right is the remote control circuit
    73s de Ed I think has the right idea
     
  14. bigkim100

    bigkim100

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    Apr 17, 2013
    And even more. So maybe I should build a LM386 DC 3-12V Micro Audio Power Amplifier Amp., and probe around the feed section of the transformer....or should I replace the Geranium transistors...or the caps??????????....what does everyone think?? r23.jpg r24.jpg
     
  15. bigkim100

    bigkim100

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    Apr 17, 2013
    Ok, so after taking off R2D2's Dome I found a series of leaf switches that added and subtracted resistance to the squeeker circuit, depending on the position of the dome. Considering the year...this was a amazingly well thought out unit. There was also a set of wipers that illuminated a led in R2's "eye".
    So now we all know how it creates the squeeking...now just why is the volume so low??


    NEWS UPDATE!!
    After trying out the unit by pressing the series of leaf switches that should be making a series of squeeks...there is NO SOUND. I assumed that since the unit gave a TINY SQEEK when first powered on, that volume was its problem...BUT NO, after the first small squeek...NO SQUEEKING...so now the battle has changed...sorry for the mis-information
     
    Last edited: May 7, 2018
  16. Audioguru

    Audioguru

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    702
    Sep 24, 2016
    You found a very cheap ebay Chinese amplifier with a fake LM386 IC on it. It shows the National Semi logo and says LM386N on it. But a real LM386N is a normal size dual inline IC with through hole pins, this one is a tiny surface mounted one that should be marked LM386MM. If it works it will probably overheat and fail soon.
     
  17. bigkim100

    bigkim100

    84
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    Apr 17, 2013
    Well it doesnt really matter, because it no longer a amplification problem, its a problem that the board really doesnt work. When the switches that I mentioned are pressed, it doesnt make the sounds it should, altho as mentioned, it makes a quiet squeek on power up
     
  18. bigkim100

    bigkim100

    84
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    Apr 17, 2013
    Anyone interested in taking this unit and repairing it for me, this is probibly over my head??
     
  19. bigkim100

    bigkim100

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    Apr 17, 2013
    Its all gone quite quiet now......lol
     
  20. kellys_eye

    kellys_eye

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    Jun 25, 2010
    LOL - you certainly fooled me..... my idea of an R2D2 sound is probably a lot more complex than the noises that board could deliver hence the thought of a COB somewhere....

    Given its age I'd replace all the electrolytic capacitors and see how that affects things.
     
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