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| electronic:equipment:gadget:lightmask [2022/11/30 19:01] – [Modification] tony | electronic:equipment:gadget:lightmask [2026/09/26 20:26] (current) – tony |
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| | <html><p style="text-align:right;">Published 24 Jan 2023</p></html> |
| | <html><p style="text-align:center;"><b><font size="6">Light Therapy Acne Mask</font></b></p></html> |
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| {{ electronic:equipment:gadget:dsc_0034a.jpg?200|Light Mask overview}} | {{ electronic:equipment:gadget:dsc_0034a.jpg?200|Light Mask overview}} |
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| ^Gadget data|| | ^ Gadget data || |
| ^Model|Light Therapy Acne Mask| | ^Model|Light Therapy Acne Mask| |
| ^Manufacturer|Neutrogena| | ^Manufacturer|Neutrogena| |
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| The power to the microcontroller is regulated by a 3.3V LDO linear regulator. The regulator and an NPN transistor are used to supply a constant current to the LEDs. | The power to the microcontroller is regulated by a 3.3V LDO linear regulator. The regulator and an NPN transistor are used to supply a constant current to the LEDs. |
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| | ==== Operation ==== |
| | As you insert the mask's plug into the "activator" the tip first contacts the B+ pin and connects it to the power regulator, powering up the "activator" - this is all before the plug is fully inserted. The LCD lights up showing "- -" at the top of the digits. The C3 100µF capacitor is also charged at this point. As the plug is inserted further the plug tip reaches the Q1 transistor contact, and the B+ to power regulator connection is connected via the plug's barrel. The C3 capacitor maintains the power during the brief connection interruptions as the plug is being inserted. After a brief delay the LCD display shows the number of sessions left (0 to 30). When the power button is held down for 1 second, if the sessions-left count is greater than 0, the transistor will be switched on, lighting up the mask. At the end of the ten minute timed session, the transistor will be switched off and the session count updated. If the plug is pulled out before the end of the session, the C3 capacitor will continue to power the activator for a few seconds. |
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| ==== Components ==== | ==== Components ==== |
| * An encapsulated micro-controller chip (COB). | * An encapsulated micro-controller chip (COB). |
| * Quartz crystal (32.768MHz). | * Quartz crystal (32.768MHz). |
| * Atmel AT93C46D serial memory chip: 64 words by 16 bits, serial EEPROM. | * Atmel {{:electronic:datasheet:atmel:at93c46d.pdf|AT93C46D}} serial memory chip: 128 bytes of 8 bits, serial EEPROM. |
| * SS8050, NPN, 1.5A power switching transistor. | * {{:electronic:datasheet:fairchild:ss8050.pdf|SS8050}}, NPN, 1.5A power switching transistor. |
| * HT7533 3.3V low dropout voltage regulator. | * HT7533 3.3V low dropout voltage regulator. |
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| And it actually works! Well had to do a bit of fiddling about to mount the LCD on the device while open, and that line between R1 and R4 actually connects to the bottom of R3, so you don't even have to scrape the copper trace bare. And I'm not actually totally sure of the sequence needed after connecting R3 to B-. The display shows a "-" over the top of the rightmost digit after touching R3. Trying to short the other two to B- (I think that's what the instruction mean) didn't seem to work easily. But shorting the top of R7 to B- resulted in two "--", one in the centre of each digit, which stayed there for a long time while I poked about, and eventually the display went back to "0" . But try, try, try again, I slipped, and not quite sure which pins got grounded, but it reverted to "30" and now works, and does 10 minute sessions!! | And it actually works! Well had to do a bit of fiddling about to mount the LCD on the device while open, and that line between R1 and R4 actually connects to the bottom of R3, so you don't even have to scrape the copper trace bare. And I'm not actually totally sure of the sequence needed after connecting R3 to B-. The display shows a "-" over the top of the rightmost digit after touching R3. Trying to short the other two to B- (I think that's what the instruction mean) didn't seem to work easily. But shorting the top of R7 to B- resulted in two "--", one in the centre of each digit, which stayed there for a long time while I poked about, and eventually the display went back to "0" . But try, try, try again, I slipped, and not quite sure which pins got grounded, but it reverted to "30" and now works, and does 10 minute sessions!! |
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| Argghh, the bottom end of J1, C9, and R3 and that wide copper trace between R1 and R4 are all connected to the regulated 3.3V supply. So the above instructions are getting you to short out the 3.3V regulator, and the power dropout simply resets the micro-controller as though it was just powered up - in fact I had occasionally noticed the display showing "-"'s briefly after power-on. That poor power regulator seems to be able to survive such abuse! | Argghh, the bottom end of J1, C9, and R3 and that wide copper trace between R1 and R4 are all connected to the regulated 3.3V supply. So the above instructions are getting you to short out the 3.3V regulator, and the power dropout simply resets the micro-controller as though it was just powered up. That poor power regulator seems to be able to survive such abuse! |
| ===== Examples ===== | ===== Examples ===== |
| {{:electronic:equipment:gadget:dsc_0048a.jpg?800|Light Mask front}} | {{:electronic:equipment:gadget:dsc_0048a.jpg?800|Light Mask front}} |
| {{:electronic:equipment:gadget:dsc_0030a.jpg?600|Light Mask switched on, front}} | {{:electronic:equipment:gadget:dsc_0030a.jpg?600|Light Mask switched on, front}} |
| {{:electronic:equipment:gadget:dsc_0029a.jpg?600|Light Mask switched on, back}} | {{:electronic:equipment:gadget:dsc_0029a.jpg?600|Light Mask switched on, back}} |
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| | {{:electronic:equipment:gadget:pc030491.jpg?400|Light Mask red LED}} |
| | {{:electronic:equipment:gadget:pc030493.jpg?400|Light Mask blue LED}} |
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| {{:electronic:equipment:gadget:pb285598a.jpg?800|Light Mask activator hack}} | {{:electronic:equipment:gadget:pb285598a.jpg?800|Light Mask activator hack}} |
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| {{:electronic:equipment:gadget:pb285620a.jpg?400|Light Mask activator hack closeup}} | {{:electronic:equipment:gadget:pb285620a.jpg?400|Light Mask activator hack closeup}}\\ |
| | This is the crude modification that hard-wires the battery negative terminal (B-, or Gnd) to the phono socket tip connection, so that the LED mask is powered on immediately when the plug is inserted. There are two disadvantages to this, first there is no longer a timed duration for the exposure, second the LEDs are run at full power which might shorten their life, and give you a stronger exposure than you were expecting. |
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| | ====== References and Additional Resources ====== |
| | * [[https://deathandthepenguinblog.wordpress.com/2018/01/03/hacking-the-neutrogena-visible-light-therapy-system-to-get-99-lives|Hacking visible light therapy system to get 99 lives]] |
| | * [[http://p1repair.com/blog/2017/09/30/neutrogena-light-therapy-mask-eeprom-hack/|Light therapy mask EEPROM hack]] |
| | * [[https://www.clien.net/service/board/use/12103135|LED mask activator modifier]] |
| | * [[https://www.reddit.com/r/AskElectronics/comments/5dvu3g/how_to_hack_neutrogena_light_therapy_mask|How to hack light therapy mask]] |
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| <html><small><p>If any referenced page no longer exists, try looking for its URL on <a href="http://archive.org">http://archive.org</a>.</p></small></html> | <html><small><p>If any referenced page no longer exists, try looking for its URL on <a href="http://archive.org">http://archive.org</a>.</p></small></html> |
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