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DIY Stompboxes => Building your own stompbox => Topic started by: composition4 on October 25, 2017, 11:49:32 AM

Title: CD4049 momentary to latching - power up in known state?
Post by: composition4 on October 25, 2017, 11:49:32 AM
Hi all,

Possibly a simple one.. is there any way to make an inverter-based latch such as this one from RG's site power up in a known state?

I'm thinking I may be able to achieve it by holding a pin high with a cap on power-up or somethuing similar but can't get my head around it at the moment.

(http://www.geofex.com/article_folders/cd4053/cd4053-4.gif)

Thanks!

Jonathan
Title: Re: CD4049 momentary to latching - power up in known state?
Post by: marcelomd on October 25, 2017, 12:36:48 PM
A few weeks ago I was looking for something similar and found this:

https://electronics.stackexchange.com/questions/186841/momentary-button-as-switch (https://electronics.stackexchange.com/questions/186841/momentary-button-as-switch)

The first answer explains how to do it. They used it for controlling a PC power supply, but the theory is the same.

In the end I used the circuit you posted as it always powered up the way I wanted. I had to play with the resistor values a bit to reduce bouncing. 
Title: Re: CD4049 momentary to latching - power up in known state?
Post by: marcelomd on October 25, 2017, 12:42:56 PM
Why not post the image here? =)

(https://i.stack.imgur.com/mAGmT.png)
Title: Re: CD4049 momentary to latching - power up in known state?
Post by: composition4 on October 31, 2017, 11:41:26 PM
Thanks mate appreciated