Re: TI-H: speaker

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Re: TI-H: speaker

well, I'm still learning electronics, but all I know is that my schem WORKS!

One question though: if current can flow both ways, then why if I have the
+ side of the speaker to 5V and - to ground, sound is made; but when I
reverse  the +/- sides, no sound!?


>For your Info...
>
>The speaker is not a diode! It is a coil of wire and a coil of wire
>doesn't conduct in only one direction. You at least need a diode!
>
>
>>I figured out what's wrong with the speaker! All you need to do is take
>>your schematic and change it as follows:
>>
>>1. take the transistor COMPLETELY OUT!
>>2. solder the clock/data wires right to the - side of the speaker!!!
>>3. forget about the signal ground wire (useless)
>>
>>I reconstructed my cart this way and it works AWESOME! It is still
>>amplified, and you don't need a transistor at ALL! Here is the
>explanation:
>>
>>The red/white (clock/data) wires use reverse logic (0=+5V 1=-?V), so in
>>normal mode, they are both at 5V! When you wire the speaker to the
>circuit,
>>the red/white wires connect to the NEGATIVE side of the speaker! (This
>>seems wierd but is not). This way, when there is 5V at the red/white
>wires
>>(- end of the speaker), no current can flow backwards through the
>speaker!
>>But when the red/white wires recieve a 1 or a negative voltage, current
>>flows from the + battery pole through the speaker and to the negativly
>>charged red/white wires! The reason why your previous schem didn't work
>is
>>because the signal ground is ALWAYS negative, so current would flow in
>>NORMAL mode (you can't just switch the poles of the speaker either,
>because
>>ground CAN'T BE POSITIVE!) The only difference between an AMPLIFIED
>speaker
>>and a normal (quiet) speaker is that the + side is wired to the battery
>>instead of signal ground (more voltage=more VOLUME!)
>>
>>Please update the schem on your page.
>>
>>As for your question on consumption levels:
>>
>>it's not the speaker that changes the brightness of your screen. I have
>had
>>the same problems on my calc, even without ANYTHING plugged into it. My
>>conclusion is that the batteries cause this. Different batteries screw
>with
>>the contrast in many wierd ways. I've tested RENEWALS and had this
>effect
>>CONSTANTLY (even during graphing!); also NiCads and alkalines. Usually
>it
>>means the batteries are getting old or weak.
>>
>>>I hope you or someone else figures this out!
>>>
>>>I'm working on the speaker problem and the NPN or whatever idea might
>>>just work, so lets hope we get it working. I have never expirienced
>this
>>>hum or buzz or whatever it is, but the cart seens to draw more power
>>>when idle than when active, meaning this reverse logic may cause the
>>>speaker to remain activated constantly when there is no signal. This
>is
>>>a major problem that I need to get fixed.
>>>
>>>On another note, I have had trouble getting newer carts to work at a
>>>reasonable level of sound. They are extremely quiet, so maybe the
>>>original is somehow different???
>>
>>Maybe your potentiometer has too much resistance. On your page it says
>to
>>use a 150K potentiometer. I found this to be WAY to much resistance! I
>used
>>a 25K potentiometer and it's volume range is PERFECT! (the one I found
>is
>>black and the dial is medium sized, so it fits perfectly into a VB
>case!
>>I'll send you a scan!)
>>
>>BTW I made an internal/external battery expander! I love it! I soldered
>one
>>wire to each +/- prong inside the calc, then ran them up the side. I
>cut a
>>smal hole (3mm x 5mm) just above the battery case. I got a battery pack
>>from radion shack and stuck two small strips of velcro up the side. To
>the
>>+/- wires, I soldered a two-pin piece of a breakaway header and covered
>it
>>in a small blob of hot glue. The battery pack velcro's to the
>>back-upperpart of the calc, so it functions as a desk-prop and doesn't
>get
>>in the way!
>
>
>Richard Piotter
>
>e-mail: richfiles@hotmail.com
>
>home page: <A
>HREF="http://www.geocities.com/SiliconValley/Lakes/5081/Richfiles.html">The
>Richfiles</A>
>
>______________________________________________________
>Get Your Private, Free Email at http://www.hotmail.com


__
Thayne Miller
Email: yomaster@geocities.com
Home Page: http://www.geocities.com/SiliconValley/Heights/5084

"Yes, well, that's the sort of blinkered, fitestine, pig-ignorance
  I've come to expect from you non-creative garbage!"
      -Monty Python
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