AU ordinary power plug, plug packs and extension cord sockets

Electrical items personally imported to Australia (eg eBay purchases) commonly do not comply with some basic mandated safety features that can be checked with a cursory visual examination.

10A Extension cord sets (AS/NZS 3120)

 

Extension cord sets sold in Australia for more than a decade must have two ‘new’ features as in the pic above:

  • insulated live pins (active and neutral); and
  • shrouded socket;

Plug tops at less than 20A (AS/NZS 3112:2011)

Plug tops at less than 20A must have insulated live pins (active and neutral), and the earth pin if fitted should be longer to make contact first. Continue reading AU ordinary power plug, plug packs and extension cord sockets

LED lighting woes

Pressed to replace working lighting with so-called ‘energy efficient’ lighting by well-meaning but narrow sighted conservationists, I recently replace about 25 CFL lamps with 12 LED MR16 lamps.

They have started failing now after a couple of years of service, perhaps 4,000 hours of service. So much for the claims of 100,000 hours… clearly preposterous.

In an effort to identify which of the switched mode power supply or LED assembly was the problem, I tried to substitute LEDs to different power supplied.

That was not a good idea, lets look at the anatomy of your typical Chinese junk MR16 LED.

Above is the complete 12W MR16 lamp with GU5.3 bipin connector on the back. Continue reading LED lighting woes

Backup for NBN VDSL access

The change from Telstra ADSL to NBN VDSL drops the POTS line that gave telephone access independent of premises power.

Telephony is now provided by an ATA integrated into the VDSL modem, and dependent on mains power.

NBN makes no definitive statements about battery backup to the node, or endurance of any battery backup. Nevertheless it appears from pics people have taken of the node cabinets that the bottom layer is batteries and it is likely that they have endurance of more than 10 hours.

1474860682982

Above, a pic of an NBN FTTN cabinet from NBN’s website, and showing batteries in the bottom layer.

NBN is not customer facing, and it seems they will provide are reluctant to provide all manner of information useful to end users, perhaps guided by lawyers who do not want to create any obligation or liability for the company… the way of modern telecommunications.

In that context, it would seem worth the risk to provide battery backup to the VDSL modem to provide broadband access to battery devices such a tablets, laptops and smartphones, and access for a POTS handset plugged into the ATA port.

The supplied modem includes a 12V DC power pack rated at 2A.

iinetgatewaycurrent

Above, measurement of the current drawn averages around 0.5A with all features running (though it may draw more current during phone ringing). Continue reading Backup for NBN VDSL access

Backup options for NBN VDSL access

The change from Telstra ADSL to NBN VDSL drops the POTS line that gave telephone access independent of premises power.

Telephony is now provided by an ATA integrated into the VDSL modem, and dependent on mains power.

NBN makes no definitive statements about battery backup to the node, or endurance of any battery backup. Nevertheless it appears from pics people have taken of the node cabinets that the bottom layer is batteries and it is likely that they have endurance of more than 10 hours.

1474860682982

Above, a pic of an NBN FTTN cabinet from NBN’s website, and showing batteries in the bottom layer.

NBN is not customer facing, and it seems they will provide are reluctant to provide all manner of information useful to end users, perhaps guided by lawyers who do not want to create any obligation or liability for the company… the way of modern telecommunications.

In that context, it would seem worth the risk to provide battery backup to the VDSL modem to provide broadband access to battery devices such a tablets, laptops and smartphones, and access for a POTS handset plugged into the ATA port.

The supplied modem includes a 12V DC power pack rated at 2A.

iinetgatewaycurrent

Above, measurement of the current drawn averages around 0.5A with all features running (though it may draw more current during phone ringing). Continue reading Backup options for NBN VDSL access

Toshiba alkaline AA leakage problems

I have used Toshiba alkaline cells in several sizes for many years (decades) and had not encountered one leaked cell… however in the last few months I have found 8 AA cells that have leaked in different devices.

The leakage has always had the same failure.

toshibaaa03Above is a view of the -ve end of the battery, ground through to expose the inner structure.

The failed batteries have leaked corrosive electrolyte, and they have all split around the circumference of the battery in the region indicated by the red arrow above. The split is common half way or more around the cell, the green seal and remnant of the rolled over case is  there, split away from the main case and covered in corrosive electrolyte residual.

This is not a failure of the green seal material, but rather the case fails.

It fails either due to internal corrosion, os weakness of the forming process. It is not clear that this area should be exposed to electrolyte anyway, so the corrosion might result from some other internal failure that releases electrolyte.

Enough reason to remove them from all devices and NEVER use these cells again.

Silver vs alkaline button cells

I purchased a new digital caliper recently (no, they are NOT vernier calipers, though modern usage seems to have misused the term vernier to the point of it having no value).

IMG_1591

A pic of the back reveals their recommendation for a battery, it is in the upper right corner of the pic “Battery 1.55V”. This is really subtle and a departure from previous practice of marking them more clearly SR44.

The nominal voltage of a silver button cell is 1.55V, an alkaline is 1.5V. Continue reading Silver vs alkaline button cells

PAROT with transformerless power supply and 230V AC relay

This article documents an implementation of PAROT (Power Amplifier Run On Timer) using Transformerless power supply for PAROT.

This PAROT uses a 230V AC relay for 230V mains switching and includes PTT switching using an FOD852 opto coupler.

The intended application is to control power to a valve PA, providing programmable heater delay, and cool down delay of power off.

Parot105

Above is the electronics built on a small piece of Veroboard. This one uses a 0.47µF cap as the power supply current requirements are a little lower than for the SSR. Continue reading PAROT with transformerless power supply and 230V AC relay

PAROT with transformerless power supply and 10A SSR

This article documents an implementation of PAROT (Power Amplifier Run On Timer) using Transformerless power supply for PAROT.

This PAROT uses a 10A SSR for 230V mains switching and does not include PTT switching, but space exists for a FOD852 opto coupler for PTT switching.

The immediate application is to control my main station power supply so that if it has been in use, is hot and fans are running, the PAROT provides in this instance a 5min cool down before powering down.

Parot100Above is the electronics built on a small piece of Veroboard.

Parot101Above is the copper side of the Veroboard. The layout is designed to accomodate another implementation using a small Triac to switch a 230V AC relay. The board has been given a heavy coat of acrylic PCB lacquer to improve voltage withstand.

The PAROT is assembled inside a small die cast aluminium box with stick-on rubber feet.

Parot102Above is a view of the interior of the box. A 430V MOV is connected across the SSR output terminals, it is not clear whether the device has internal protection (Chinese product, very brief data). The LED / momentary switch on the right is the only control and indicator for PAROT operation. Note that because of the transformerless power supply, everything inside the box is potentially at mains voltage… a fact that must be kept in mind when working on it. An isolation transformer is a worthwhile tool for working on these type of things. Continue reading PAROT with transformerless power supply and 10A SSR

Transformerless power supply for PAROT

This article documents design of a capacitive transformerless power supply for operating low voltage, low power logic from power mains. The intended application is PAROT (Duffy 2013), though it has potentially wider application.

(Microchip 2004) gives a method for design of a capacitive transformerless power supply for operating low voltage, low power logic from power mains. The equations seem simplistic for a circuit whose apparent simplicity belies the complexity of an optimal design that properly tolerates supply voltage and load variations. For that reason, a SPICE simulation was used to refine a design.

The immediate application is for the PAROT chip driving a 40A SSR.

Clip 197

Above is measured characteristic of a Fotek 40A SSR, it seems typical of several similar types on hand. It appears that much smaller SSRs in the 2A range require fairly similar current. Continue reading Transformerless power supply for PAROT