# Generating 50hz Freq Question.

Discussion in 'Electronic Basics' started by Wilhelm Lehmann, Jun 14, 2004.

1. ### Wilhelm LehmannGuest

Hi,

I am relatively new to electronics, but understand the basics at least.
Using a 555 and R + C, I can create a 50hz oscillation, but it seems not to
be very accurate.

I understand using crystals is much more acurate, but need to find how to
manage the oscelation at 50hz. Using a PIC16F74 works but defeats my goal of
making it simple. ( ie no programming) Is there a circuit that I can use,
maybe with a cmos counter using a 4mhz (or other value) crystal to generate
the 50hz ? (switching 2 transistors on and off alternativly)

Wilhelm

2. ### John FieldsGuest

---
You can get an Epson C-2 25.60000K-P (25.6kHz) crystal and a 74HC4060
ripple counter/oscillator from Digi-Key, and Q9 of the counter will
give you a 50Hz output once you get it to oscillate.

check page 12 of:

http://www.philipslogic.com/products/hc/pdf/74hc4060.pdf

for a schematic of a typical CMOS crystal oscillator.

3. ### Wilhelm LehmannGuest

Thank You very much. Just what I needed.

4. ### CFoley1064Guest

Subject: Generating 50hz Freq Question.
Of course, the customary solution for this is to run off the 50 Hz line
frequency. Otherwise, the customary answer is to generate an interrupt off of
your microcontroller timer/counter using the crystal-based uC clock frequency.
But somehow, I don't think that's what you're looking for.

Given that, I don't think there's a one-chip solution that will get you where
you want to go. A crystal frequency of 2.048 MHz will get you a two-chip
solution (view in fixed font or M\$ Notepad):

50 Hz From Crystal or Oscillator
.-----------------.
| | .--------------.
..-----o-----. | | | |
| | | CLK /2^12| | |
| 2.048MHz o----o CD4040 o------oCLK |
| | | | | CD4017 |
| | | | | |
'-----o-----' | | .-oEN |
| | | | |
| | | | OUT/10 |
| | | '-------o------'
'-----------------' | |
=== |
GND |
|
|
o
50 Hz
Squarewave

A cursory scan doesn't show any crystals at this frequency from the usual
hobbyist suspects, but you can get an SMD TTL/CMOS-compatible clock oscillator
at this frequency from Mouser for \$2.31 USD (P/N 549-C3290-2.048).

offer more advice on what to do with the 50 Hz signal to drive your output.

Have fun.

Good luck
Chris