Frequency Generation from crystal oscillator - Page 1
Forum section: electronics / projects

author: Sangharsh Sharma
author_rank: Contributor
timestamp: October 10, 2018, 02:17:15 am
content: Hello Guys! I want to generate a 1Hz frequency using a quartz crystal oscillator. But, I'm not quite familiar with the device and I'm confused about how to connect the circuit appropriately. Also, I couldn't find a crystal oscillator of 1hz. When I looked up at sites, it said we needed to divide the frequency..What does it mean? Would appreciate your help

author: hamster_nz
author_rank: Super Contributor
timestamp: October 10, 2018, 02:35:42 am
content: Be prepared for some sensible and not-so-sensible answers. You reallly havent told use why you need the signal, and how you intend to use it.My suggestio. Is to look for a circuit that uses a 32768Hz crystal, and then uses 74LS series flipflops to divide it by 32,768 to give 1Hz

author: Circlotron
author_rank: Super Contributor
timestamp: October 10, 2018, 02:37:17 am
content: https://dmohankumar.wordpress.com/2012/05/13/design-your-circuit-part-ii-cd-4060-timer/

author: DaJMasta
author_rank: Super Contributor
timestamp: October 10, 2018, 03:19:19 am
content: Yep, as mentioned 32.768kHz crystals are used for timekeeping because of the easy binary counter conversion to 1Hz. You could do it with anything, but being a power of 2 means you only need to watch a single output bit on a counter.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: October 10, 2018, 03:23:25 am
content: A PIC or similar low-cost microcontroller and a few lines of code can do it.

author: cdev
author_rank: Super Contributor
timestamp: October 10, 2018, 03:35:15 am
content: For a few bucks you can buy a chip that gets you 9/10's of the way there (all the way there if you can settle for 2 Hz.) and get a free GPS thrown in too. The only drawback, you cant be in a basement or inside a metal building (or inside a metal box!) or underground and expect it to work well.Also you need an antenna. The cheapest kind of GPS antenna will do.You can do all the rest with a PIC chip.

author: Sangharsh Sharma
author_rank: Contributor
timestamp: October 10, 2018, 03:47:46 am
content: Actually, I need it for building a digital clock. First I need to get 1 Hz frequency, therefore I needed it. Initially, I had already done the job using a 555 timer. But, since it uses resistors and capacitors, there would be errors with time even due to small temperature changes. So, my project co-ordinator told me to use a crystal oscillator.

author: DaJMasta
author_rank: Super Contributor
timestamp: October 10, 2018, 04:23:17 am
content: If it's a plugin clock, you can actually use a divider on the input mains frequency (60Hz or 50Hz, depending on where you live). The power company keeps it quite stable - not quite to the level of GPS, but in the long term better stability than a crystal offers since it's a disciplined frequency source.

author: hamster_nz
author_rank: Super Contributor
timestamp: October 10, 2018, 04:26:37 am
content: This might help....http://www.hackersbench.com/Projects/1Hz/

author: cdev
author_rank: Super Contributor
timestamp: October 10, 2018, 07:52:20 pm
content: You could use one of the DS3231 (RTC) modules that gives you the 32 KHz output as well as a standard RTC (Not all do - those that do clearly label it). They are very inexpensive (sometimes just $2-3 and often they even come with a lithium battery.The accuracy will typically be very good.Far better than the typical quartz crystal clock in a PC. To use it you will need one of almost any of the micro controller or SBC boards, (any) raspberry pi, 'arduino', blue pill (STM32103f series), etc. So basically you get your 32k oscillator plus a free clock connected to it (although its not appropriate to use that to check its accuracy against unless you are just checking the logic you are using, because any frequency error will be reflected in the 32k signal. But the ones that I have bought have worked out well.)