Generating a 38kHz Sine Wave

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brightnight1

Joined Jan 13, 2018
81
I'm trying to simulate and then build a circuit I found in a Vishay application note. In the schematic there is a 38 kHz sine wave going into a NAND gate. What options are there for generating a sine wave? Are there chip solutions? I think I want an actual sine wave and not a square wave from a 555 timer or something like that.


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dl324

Joined Mar 30, 2015
13,809
National Semiconductor AN-31:
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If you integrate a square wave you get a triangle wave. If you integrate a triangle wave, you get a sine wave.
 

Papabravo

Joined Feb 24, 2006
17,530
I assumed it was a sin wave because of the drawing but looks like a sine wave into a gate is a bad bad idea...
A couple of points:
  1. Looks more like a square wave with rounded edges.
  2. 74xx parts usually have a power supply of +5 Volts and GROUND.
  3. Sinewaves tend to have positive and negative peaks with an average value of 0 Volts aka GROUND.
  4. The gate does not explicitly show the power (+5V) and GROUND (0 V) connections, but they damn skippy need to be there.
 

DickCappels

Joined Aug 21, 2008
8,132
Don’t worry…if you drive an LED with a square wave it is pretty easy to turn it into a sine wave in the receiver/detector if it doesn’t happen automatically.
 

crutschow

Joined Mar 14, 2008
28,458
Note that the 38kHz for a remote control may require tweaking of a 555 astable to get it within the required frequency range.
 
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