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IPL (Intense Pulsed Light) Hair Removal Device Internals

IPL hair removal is rather similar to laser hair removal – high energy photons are directed into the hair follicle to heat the cells up until death occurs, stopping the hair from growing. These units use high-energy Xenon flash tubes to do the job, and operate in exactly the same fashion as a camera flash. Here are the internals of such a device.

Mainboard
Mainboard

The mainboard in the top of the unit deals with all the functions of the device. There’s a main microcontroller, which in this case is an unmarked IC. The UI is a simple LED display, showing the number of shots on the tube remaining. These units come with 500,000 shots programmed in. The limit is to prevent the Xenon tube from exploding when it reaches end of life. In the case of these devices, after the counter reaches zero, the unit is disposed of. The trigger transformer is visible at the right of the board, along with it’s capacitor. This is triggered by a small Thyristor at the bottom edge of the board just to the right of the LED display. There are some power handling components on the left side, along with the main switching FET & gate drive IC for the high voltage supply.

There are several power settings, and the power itself is varied by the voltage on the main capacitor, from around 270v to 400v. There’s no dedicated switching IC here – The microcontroller generates a 65kHz square wave, from 0-50% duty cycle to drive the main switching FET. There’s a resistive feedback network to regulate the boost converter’s output voltage.

Mainboard Bottom
Mainboard Bottom

There’s less on the bottom of the PCB, apart from the connections to the PSU, cooling fan, capacitor & trigger button, there is the transformer for the HV supply. At the lower centre, is the driver IC for the LED display.

Flashtube
Flashtube

The flash tube is mostly hidden inside a plastic shroud with an amber filter glass on the front to provide the correct light spectrum. The metal ring around the outside edge is part of a capacitive detection mechanism that prevents the tube firing unless it’s placed against skin. I have no doubt that the intensity of light from these devices could quite easily cause eye damage. Even absorbing the energy into the skin is slightly painful – hitting black tattoo ink with it feels like a needle prick!

Cooling Blower
Cooling Blower

Since the flash tube passes such a large pulse of energy, it is force cooled by this small blower which sits under the mainboard, and directs air into a slot in one end of the tube housing. The other end allows the air to exhaust back out, taking the heat with it. This fan runs continually while the device is powered on. This fan shifts an impressive amount of air for it’s size.

Flash Capacitor
Flash Capacitor

Finally, there is the main storage capacitor for the flash tube. This sits down in the handle, and is massive at 450v 680ยตF, providing 69 Joules of energy at full charge. In the case of this unit, the energy is variable from 25-55J.

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HLD-100+ Refrigerant Leak Detector Lithium Battery Mod

My refrigerant leak detector has one flaw – from the factory it uses C-size alkaline cells. Considering I don’t normally stock these (nothing else I have uses them!), and they’re big & heavy, I decided to do a modification to run the unit from lithium cells instead. This would allow charging via USB.

Factory Battery Compartment
Factory Battery Compartment

Here’s the factory moulding, with extensive strengthening ribs around the battery compartment. Some of this will have to be removed to get the new cells into place. Cue the scalpel! The battery contacts will also have to be removed from the casing.

Battery Fitted
Battery Fitted

After removing some of the plastic, the new cells are a snug fit inside the battery space, with plastic ribs still in place to stop them falling out of the end of the case.

Lithium Charge IC
Lithium Charge IC

A small hole drilled in the back of the unit allows access to the USB port for charging, through this TP4056 3.7v charge module.

Board Refitted
Board Refitted

A bit of rewiring, and the original battery connector is refitted to the board.

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Blog Housekeeping & Changes

It occurred to me the other day that I’ve been running this blog now for over 10 years! This is the second iteration, as the first was lost in a server crash shortly after it went live. (Wasn’t so good with backups back then!). In that time the traffic to the blog has grown exponentially, who’d have thought that people would actually like reading most of the waffle that comes out of my brain! ๐Ÿ˜‰

2020 Stats
2020 Stats

It seems the global Covid-19 Pandemic actually had an effect on my visitor numbers as well.

At the moment things are becoming a little cluttered on the back end, and there are a few errors that need sorting on the front end – thanks to some of my readers for pointing some of those out!

Site Theming

I’ve also been using the same theme for most of that time, but it’s beginning to show now with many updates over the years, and no updates to the theme code, that I’m going to start having some issues with the next versions of PHP, so this will have to change. This does join up with another project I have going, for a small webshop. The current theme unfortunately isn’t compatible with the most popular WordPress commerce plugins.

Broken Downloads

Thanks again to my readers for catching this one! It seems most of the downloads on the site have become broken, although I’m not sure why. I have changed over the Download plugin, and I am in the process of slowly moving over the shortcodes to the new system, so they will all be operational again.

On-Disk Size

Over the last decade or so of running, this blog has grown massively in size on disk – the usage currently stands at around 80GB. I really do need to reduce this footprint, so some time will have to be taken going through the backend filesystem to prune out any crap.