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Re: [N8VEM-S100:2348] Decoupling caps
- To: n8vem-s100@googlegroups.com
- Subject: Re: [N8VEM-S100:2348] Decoupling caps
- From: David Riley <frave...@gmail.com>
- Date: Fri, 7 Feb 2014 13:41:11 -0500
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On Feb 7, 2014, at 12:49 PM, nbreeden <nbre...@me.com> wrote:
> I'm curious as to others opinions about decoupling caps. These are typically 0.1uF disc caps which is what is specified for all of the various boards in the N8VEM family.
>
> In a grab bag I recently bought I found a large number of 0.01uF and 0.2uF disk caps (over 1000 of each). What are your thoughts on using these?
Don Lancaster's TTL Cookbook (a decent reference for a lot of things) recommends 0.1-0.01uf ceramic disc caps for TTL (he specifically recommends one for every 4 SSI packages and one for every 2 MSI packages, which isn't a bad guideline as these things go). Don't go too large, or the lead inductance will overcome any gains you get from extra capacitance and you'll also run the risk of the resulting LC circuit resonating and causing ringing on the power lines, which is a Bad Thing.
In short, go for .01 uF by default. .2, which isn't something I see often (sure it's not .22?) is probably still OK, and something I see a lot in production circuits (which, of course, doesn't mean it's right).
- Dave