[TI-H] Re: [A83] Re: OT: Clock with resistor and capacitor


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[TI-H] Re: [A83] Re: OT: Clock with resistor and capacitor




Peter,
	Not sure if this is what you need.  They are using a LM555 chip
however they go into explaining how the chip works and give equations
for it about halfway through.  It should offer some insight into how to
do it.  For the Switch...because you wont be using a chip like they are
just use a transistor that is rated for the right voltage.  Hope this
works for you.  If not let me know and I'll see what else I can find.  I
do not think it is possible to do without a transistor, b/c the
capacitor needs to be able to charge then drain.  It is drained by
shorting it to ground.

Regards,
Cullen Logan

-----Original Message-----
From: ti-hardware-bounce@lists.ticalc.org
[mailto:ti-hardware-bounce@lists.ticalc.org] On Behalf Of Peter-Martijn
Kuipers
Sent: Tuesday, October 09, 2001 3:05 PM
To: ti-hardware@lists.ticalc.org
Subject: [TI-H] Re: [A83] Re: OT: Clock with resistor and capacitor


> At 05:01 PM 10/9/2001 +0200, you wrote:
> 
> >A few posts ago, someone mentioned that the clock frequency in the
> >TI-83(+) was done with a resistor and a capacitor.
> >Can someone give me more info about it, since I need to have a simple
> >clock generator for a (+5V DC) cirquit I'm making.
> 
> 
> For a clock, a capacitor will fire on a predictable interval.  There
is a 
> formula by which you can take capacitor value and voltage (an perhaps 
> amperage) and get a clock frequency.  The resistor is just there to
fix the 
> formula to the right clock given the other parts of the circuit.  If
you 
> need help with electronics stuff, there are a number of good web
sites, or 
> the TI-H list.

Could someone give me the formula and schematic on how to connect it?

Thanx,
--Peter-Martijn Kuipers 







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