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CircuitGizmos

Guru

Joined: 08/09/2011
Location: United States
Posts: 1425

Posted: 01:31am 24 Jan 2012

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Gizmo is right.

Unregulated wall warts tend to change in voltage as their current changes.

Micromites and Maximites! - Beginning Maximite

djuqa

Guru

Joined: 23/11/2011
Location: Australia
Posts: 447

Posted: 01:42am 24 Jan 2012

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Yes some of them can be 10% or more RIPPLE factor
with up to 10v output with little load current.
Good 5v plug packs are CHEAP buy One.Edited by djuqa 2012-01-25

VK4MU MicroController Units

pcaffalldavis

Senior Member

Joined: 17/10/2011
Location: United States
Posts: 187

Posted: 11:55am 25 Jan 2012

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Well I have a few 4.5 volt wall transformers for old sony discmans, remember those? I'll check their voltage, but do you think I can use 3 D cells for the battery back-up for when power goes out? I don't know of any 5 volt batteries. I wonder if 4.5 volts will be enough? What do folks suggest for battery back-up for CGMMSTICK1's when line power goes off?

Pete in Hyder

We're all here 'cause we're not all there.

rhamer
Senior Member

Joined: 06/06/2011
Location: Australia
Posts: 174

Posted: 09:16pm 25 Jan 2012

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pcaffalldavis said Well I have a few 4.5 volt wall transformers for old sony discmans, remember those? I'll check their voltage, but do you think I can use 3 D cells for the battery back-up for when power goes out? I don't know of any 5 volt batteries. I wonder if 4.5 volts will be enough? What do folks suggest for battery back-up for CGMMSTICK1's when line power goes off?

Pete in Hyder

Run the whole thing from a UPS, they are very cheap these days and solve all the change over and charging issues.

Cheers

Rohan

Rohan Hamer
HAMFIELD Software & Hardware Solutions

Makers of the Maximite Expander.

http://www.hamfield.com.au

TassyJim

Guru

Joined: 07/08/2011
Location: Australia
Posts: 6098

Posted: 11:48pm 25 Jan 2012

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The MCP1700 regulator on the CGMMSTICK1 is a very low dropout one so yes, you could run it off 4.5V with room to spare for an isolating diode.
With a shottky diode (~0.35V volts drop) you could let the battery volts drop to 4.0 before thing went cranky.
I have a need for 12V as well so I run everything of 12V with 8 and 5 volt regulators as required. The maximite monitors the battery volts and if the power has been off for too long the maximite turns off some of the higher current drawing devices such as cameras and the network switch.

Jim

VK7JH
MMedit MMBasic Help

3buns
Newbie

Joined: 16/07/2012
Location: United Kingdom
Posts: 8

Posted: 03:05am 16 Jul 2012

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Hi all, new member here, great forum!
I received my CGMMSTICK1 in the post here in the UK the other day.

I am planning to build a scaleable retro games console with it. My question is regarding the 3.3v available on PIN 1. I have read that the device will draw 125mA'ish,does this include powering the SD card? The MCP1700 I read is rated at 250mA. I would like to draw up to 50mA from the 3.3v pin for joystick resistor pullups, is there enough headroom on the regulator for this, or should I really go for an off board regulator?

Many thanks, Kurt

CircuitGizmos

Guru

Joined: 08/09/2011
Location: United States
Posts: 1425

Posted: 09:29am 16 Jul 2012

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Best to play it safe and use an off-board regulator. SD card access is sensitive to voltage dips on the 3.3V line.

Micromites and Maximites! - Beginning Maximite

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