Probably a stupid question.... DC in to a full wave rectifier? - Page 1
Forum section: electronics / beginners

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: September 07, 2015, 05:32:17 am
content: Will using a bridge rectifier help reduce any noise on a DC supply whether it be linear or switching, I meant the point is to convert any AC signal to DC so does this apply to the small amount of AC offset in DC supplies? I know filtering and ferrite is the usual path for clean power but will using a rectifier help anything at all?I have a kit I want to build and it it sort of ohm/volt nutting orientated I will tak about it some more another time but I wanted to ask this while it was on my mind... gotta have clean DC for a 24 bit dac with a 1.2v reference.

author: fubar.gr
author_rank: Unknown
timestamp: September 07, 2015, 06:46:56 am
content: It will have the same effect as inserting two silicon diodes in series.The output will be ~1.2 Volts lower. Noise will pass through unfiltered.

author: Jeroen3
author_rank: Super Contributor
timestamp: September 07, 2015, 06:56:26 am
content: It'll only reduce the impact of dips. Since energy stored in the smoothing capacitors is not able to flow back.

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: September 07, 2015, 01:51:23 pm
content: Ok thanks for the answers, im not an EE so the idea somewhat made practical seanse but i couldnt find anything on the net and assumed it must not be a great idea

author: TimFox
author_rank: Super Contributor
timestamp: September 07, 2015, 03:56:08 pm
content: There are many switch-mode devices where the single-phase AC input passes through an on-board bridge to a "bus" capacitor, and the switching circuits send that voltage through appropriate devices (and possibly transformers) to the load. In high-power applications, such as motor drivers, I have used a three-phase AC source, through an external "six-pulse" bridge, to apply DC (with roughly 10% ripple) to the single-phase input to reduce the bus ripple.

author: joeqsmith
author_rank: Super Contributor
timestamp: September 07, 2015, 04:13:18 pm
content: Saw in Nuts and Volts ( I think) where they used a bridge with DC. Not for a filter but allowed them to install batteries in both directions without damage. I remember thinking that I would rather not have the losses.http://www.nutsvolts.com/

author: rsjsouza
author_rank: Super Contributor
timestamp: September 08, 2015, 02:47:25 pm
content: Quote from: Jeroen3 on September 07, 2015, 06:56:26 am+1. You can even replace the bridge with a single diode, with the advantage the voltage drop will be halved (and you save three diodes).Quote from: joeqsmith on September 07, 2015, 04:13:18 pmThat is a very useful solution if it is an unenclosed standalone board that can be powered by wires (on a lab environment) or by unknown voltage sources (the typical plugpacks with reversed polarity, for example). That can also be replaced by a single diode with the advantages above (less drop and component count), with the difference that a polarity reversal will simply cause the board to not work.These scenarios do not seem to be the case for the OP, though.