Replacing the crystal in a Seiko V158-0AD0 watch

I have a Seiko V158-0AD0 which works very well, and I recently noticed the crystal was scratched more than the case… so a strong hint that it is an ordinary mineral glass crystal.

Searching the net, I could find that the Seiko part number for the original crystal is 310P03HN0 which indicates a diameter of 31.0mm but it does not have the thickness encoded simply. I could not find any articles giving the thickness of the part… so measurement was needed.

Above, the original crystal measures 1.6mm. A ‘standard’ 1.5mm sapphire crystal should be just fine. Continue reading Replacing the crystal in a Seiko V158-0AD0 watch

Reassembling a certain common chainsaw clutch

I managed to drop a chainsaw clutch and it separated into its component parts.

Thinking there would be a simple trick to this, I consulted Youtube. It turns out that reassembling these has proved a challenge for many people, and their online posts informed as to what approaches don’t work well, describing the many hours spent trying to reassemble. One online expert advised buy another, they are so cheap.

Above is a clutch of the type I will discuss, mine is from a 45-58cc Chinese chainsaw. There are variants, and the technique may be adaptable to them. Continue reading Reassembling a certain common chainsaw clutch

Sydney harbour is a beautiful place

One of the trips I am known to take is to Manly for lunch.

Above is a pic taken whilst waiting for the train home at Circular Quay. On the right is the ferry Freshwater arriving from Manly. The Opera House is just visible on the right north of the ‘toaster’ (one of the eyesores on the harbour).

It was a sparkling day on the harbour (Port Jackson) which bought back memories of many happy days boating and sailing, it is a beautiful waterway.

Manly is about 30min north east, 12km over the water, just on the north side of Sydney heads.

It is challenging to get pics on the ferry as tourists push their phone in front of your face to take videos, 5 to 10 minutes as a time.

Above, the route is from home to Bowral station by car, diesel train (Endeavor railcar) to Central, electric train on the Sydney underground to Circular Quay, and ferry to Manly. The return journey was similar but electric train from Circular Quay to Campbelltown then diesel train to Bowral. The round trip is just on 300km and nearly three hours for each direction of travel.

An interactive zoomable map is available. Zooming in around Sydney and a little south will show track jumps due to underground rail.

The track was captured with a Holux RCV-3000 GPS logger, logs downloaded with BT747 (Chinese firm Holux is defunct and so is their application which is now locked out of its maps provider).

Holux web site missing / offline, Holux ezTour crippled

I have had a couple of Holux GPS loggers for some time, a RCV3000 and GPS245+.

They come with a neat little application called Holux ezTour for Logger.

Over time, the application has been unreliable, mostly knock on effects of Google Maps licencing and Holux’s failure to obtain and distribute the appropriate licence keys. Continue reading Holux web site missing / offline, Holux ezTour crippled

Refurbishing the push button in action cam cases

In my experience, action cam underwater / weatherproof transparent cases have buttons that are quite difficult to use. This seems mostly because they are assembled with no lubricant.

Above, the button in the genuine Sjcam SJ8  has a stainless spring, shaped washer, two 6x2x2mm orings, and a 2.5mm E clip. This pic shows that the thing is assembled dry which makes operating pressure high, and in any event not smooth as the button shaft is not particularly smooth. Continue reading Refurbishing the push button in action cam cases

Garden hose couplers – there has to be a better way

A continuing frustration is garden hose maintenance.

We use reinforced hose that comprises essentially three layers, an inner plastic layer, a braided fibre reinforcing layer and another layer of plastic. Though these layers are bonded in new hose, there is potential for them to separate in service resulting in the reinforcing braid pulling back into the hose length and allowing the hose to expand in diameter at that point (lacking the benefit of the reinforcement). At this point failure of the hose by bursting is inevitable, sooner rather than later.

Some hoses are supplied fitted with factory crimped ferrules, and experience is that they have lasted well except that the fittings are plastic and break if subjected to rough treatment.

User serviceable screw collets fail, either through failure of the collets, or just the outcome of the screw collar loosening and resultant pull-back of the reinforcing braid.

What is needed is a tough and durable coupler with an easily applied ‘permanent’ clamp.

I have conducted a trial of brass fittings modified to remove the screw collar and nylon collet, then used with a stainless steel stepless one ear clamp.

Above at left is the unmodified coupler, and at right the coupler with the collet and screw collar discarded, thread turned off the coupler, and a one ear clamp for installation. Continue reading Garden hose couplers – there has to be a better way

Cheap Chinese wristwatch #1

I bought an inexpensive Chinese manual wind wristwatch for my grandson. It is a skeleton style watch based on the communist Tongji movement.

Above, the watch looking pretty flashy in gold coloured finish. The gold plate wore off the band in just a few days to reveal a brass band tarnishing by the hour. The bezel is probably base metal and will corrode in no time. Continue reading Cheap Chinese wristwatch #1

Ham grade analysers and VNAs often use unconventional meanings for well known terms

Lets use a simple test circuit to review the meaning of some oft misused terms associated with VNA and antenna analyser measurements.

Above, the test circuit is a nominally 220pF COG capacitor connected between tx and rx ports of a two port VNA. An extra 1Ω series resistance is included to model the likely effect of capacitor ESR. Continue reading Ham grade analysers and VNAs often use unconventional meanings for well known terms

Mandarin & Lime Marmalade

I couldn’t help myself, Mandarins are falling and I had to try a marmalade of Mandarins and Limes. I made a small batch of marmalade using 50% Tahitian Lime and 50% Imperial Mandarin. Raw sugar was one third the added sugar to impart a darker colour.


The marmalade is light coloured, sweet and tangy. Continue reading Mandarin & Lime Marmalade