malykh.com notes

2026-04-29

Romoss Solo 5 power bank (2017)

In 2017, I purchased the Romoss Solo 5 (10000 mAh power bank) for $10 with free shipping.

It was cheap, but the main reason was the internals of the Solo 5. This power bank contains five standard 18650 batteries.

(source video)

I knew about this, and I wanted to disassemble the power bank and use the batteries in other devices. It could be very profitable.

Although I didn't initially need a power bank, this one turned out to be useful. So, I kept it without taking it apart. And, despite its inconvenient microUSB port (input for charging), the power bank is still used today.

Image albums:

Electronics

2026-04-27

Maxxis Rambler 700x50c: Mounted tubeless

I mounted the Maxxis Rambler 700x50c tires on the Koozer 29" wheels.

The tires were mounted tubeless without any problems.

The tire carcass width is 51mm (2.0") on these i27 rims at 3 bar (43 psi).

See also related notes:

Maxxis Rambler 700x50c (2026-04-17)
Koozer XM1850 (622x27) wheelset (2024-06-29)

Image albums:

Bicycle

2026-04-25

Sony a7c: v2.03 firmware

Firmware version 2.03 has been released for the Sony a7c.

As for v2.02, the change list for v2.03 is obscure:

===

Improves the operational stability of the camera

===

As usual, I will wait for some time before updating.

See also related notes:

Sony a7c: v2.02 firmware (2025-09-11)
Sony α7c (Alpha 7C, a7c) (2022-03-18)

Image albums:

Sony a7c

2026-04-23

ISCO Iscovitar 50/2.8: Samples [2] - FF - f/2.8 - Two types of focusing

Camera: Sony a7c (FF, 24MP)

Lens: ISCO Iscovitar 50/2.8 at f/2.8

The ISCO Iscovitar 50/2.8 has a simplified focusing mechanism. Only the front optical element moves. So, like the Riconar/Rikenon 55/2.2, two types of focusing can be used: with the built-in mechanism or with the lens adapter. See more details.

There are comparisons between these the two types of focusing.

(lens focusing)

(adapter focusing)

(lens focusing)

(adapter focusing)

(lens focusing)

(adapter focusing)

See also related notes:

ISCO Iscovitar 50/2.8 (M42x1/45.5): Triplet with simple focusing mechanism (2024-05-21)
Riconar/Rikenon 55/2.2: Two types of focusing and background blur (2023-11-27)
Noname Leica M-Sony FE/E close focus (helicoid) adapter (2023-07-30)
Riconar/Rikenon 55/2.2 (K): It's not a triplet (2023-06-21)

Image albums:

ISCO-Göttingen Iscovitar 50/2.8

2026-04-21

Koozer 450: Six-bolt vs Centerlock

Which bike rotor to choose? Six-bolt or Centerlock? It is often a matter of preference. However, some hubs are designed differently depending on the type of rotor.

For example, there are front Koozer 450 hubs in MTB versions (based on a 15 mm wheel axle).

Hubs for six-bolt rotors use bigger 18307 (18x30x7 mm) bearings. And there is an internal hub axle (15x18 mm) that goes through the bearings.

(J-bend spokes)

(Straight-pull spokes)

Hubs for Centerlock rotors use smaller 6902 (15x28x7 mm) bearings. These hubs have no internal axle going through the bearings, just a spacer sits between them.

(J-bend spokes)

(Straight-pull spokes)

This applies to the front MTB hubs only. Regardless of rotor type, the front/rear road versions and the rear MTB versions of the Koozer 450 use 6902 bearings and an internal hub axle (12x15 mm).

See also related notes:

Koozer XM1850 (622x27) wheelset (2024-06-29)

Image albums:

Bicycle

2026-04-19

Tonigy: Apache 2.0 license

I chose the Apache License v2.0 for Tonigy.

The source code is available, you are welcome.

See also related notes:

Tonigy source code [OS/2, 2001-2002] (2023-12-03)

2026-04-17

Maxxis Rambler 700x50c

I used the Kenda Small Block Eight 29x2.1 tires for two years. During that time, they wore out. I decided to replace them with similar tires, but 120 TPI.

I bought the Maxxis Rambler 700x50c (50-622, equiv. to 29x2.0 in terms of MTB).

They are 120 TPI, foldable, of course.

Recommended pressure: 2.5-3.4bar (35-50psi)

Weight: 628g and 654g (each, without packaging).

See also related notes:

Maxxis Rambler 700x50c: Mounted tubeless (2026-04-27)

Image albums:

Bicycle

2026-04-15

Samsung NX 16/2.4: Samples [2] - APS-C - f/5.6

Camera: Samsung NX20 (1.5x crop factor, 20MP), Samsung NX300M (1.5x crop factor, 20MP), Samsung NX500 (1.5x crop factor, 28MP)

Lens: Samsung NX 16/2.4 at f/5.6 (24 mm equiv.)

The profiled lens correction is disabled in the raw converter.

(NX20)

(NX300M)

(NX500)

(NX20)

(NX500)

See also related notes:

16-20-30 (добавлен Samsung NX 16/2.4) (2012-11-09)

Image albums:

Samsung NX 16/2.4

2026-04-13

135-120 film adapters

These are two pairs of adapters to install 135 (35mm) film into a 120 film (medium format) camera.

Unfortunately, they are not compatible with my old Kiev-6S camera.

I successfully loaded a 35mm film, but when I cock the shutter, it goes very tight. I stopped because I was afraid of breaking something.

See also related notes:

Kiev-6S: Budget medium format film camera (2025-06-11)

Image albums:

2026-04-11

VIOFO A119 Mini 2: GPS module

The GPS module of the VIOFO A119 Mini 2 is also serves as a mount. Therefore, an additional GPS module must be purchased to mount the dash cam in a second car.

I bought a module claimed to be compatible with the VIOFO A119 Mini. However, it is exactly the same as the Mini 2's module.

And it works well with my VIOFO A119 Mini 2.

By the way, I use GPS for clock synchronization only.

See also related notes:

VIOFO A119 Mini 2: My new dash cam (2026-02-09)

Image albums:

Video

2026-04-09

Kenda Small Block Eight 27.5x2.1: i19 vs i35

The Kenda Small Block Eight 27.5x2.1 tires mounted on different rims:

The left wheel has a 584x19 (i19 - 19mm internal) rim.

The right wheel has a 584x35 (i35 - 35mm internal) rim.

The tire carcass width:

i19: 52.1mm (2") at 4 bar (58 psi)

i35: 58.4mm (2.3") at 4 bar (58 psi)

The outer tire diameter is also slightly larger with the i35 rim.

See also related notes:

Kenda Small Block Eight 27.5x2.1 tires (2025-07-31)

Image albums:

Bicycle

2026-04-05

Pentax Q 07 11.5/9 Mount Shield Lens: Samples [2] - 1/1.7" - f/9

Camera: Pentax Q7 (1/1.7", 12MP)

Lens: Pentax Q 07 11.5/9 Mount Shield Lens f/9 only (53mm equiv.)

The larger sensor provides better resolution in the center, but the area off-center is more blurred. The lens still needs light, with f/9 and 1/100.

(ISO 1250, Noisy!)

See also related notes:

Pentax Q 07 11.5/9 Mount Shield Lens (2025-08-21)

Image albums:

Pentax Q 07 11.5/9 Mount Shield Lens

2026-04-03

MIT license for some of my projects

I have applied an MIT license to my projects:

724mix - OS/2 mixer for YMF724 [OS/2, 2000-2001]:

https://github.com/malykhcom/724mix

Win95Key plug-in to control T&V HappyPlayer [OS/2, 2002]:

https://github.com/malykhcom/w95k_tvh

malykh-geo-ep source code [Java, 2009-2010]:

https://github.com/malykhcom/malykh-geo-ep

malykh-drb3-reader [GitHub]:

https://github.com/malykhcom/malykh-drb3-reader

See also related notes:

malykh-drb3-reader [GitHub] (2026-01-25)
724mix - OS/2 mixer for YMF724 [OS/2, 2000-2001] (2024-03-11)
Win95Key plug-in to control T&V HappyPlayer [OS/2, 2002] (2024-01-19)
malykh-geo-ep source code [Java, 2009-2010] (2023-12-15)

2026-04-01

Shimano B05S: Disc brake pads

New disc brake pads Shimano B05S:

Old pads Shimano B01S (OEM from Cujo):

I am not sure whether the new pads are genuine or fake. They have worked well overall since I started using them in autumn. However, they sometimes squeak in rainy or snowy conditions.

See also related notes:

Cannondale Cujo 1 (2018): компоненты и спецификация (2018-10-14)

Image albums:

Bicycle

2026-03-29

M39x1 extension tubes

I have several sets of M39x1 extension tubes.

1. Old four-tube set, USSR, KMZ (КМЗ).

Tube lengths: 5mm, 8mm, 16.4mm, 26mm.

2. Old four-tube set, USSR, FED (ФЭД).

The same tube lengths: 5mm, 8mm, 16.4mm, 26mm.

Why is the tube length 16.4 mm? This tube is used to mount earlier Zenit SLR M39x1/45.2 lenses to M39x1/28.8 rangefinder cameras: 45.2 - 28.8 = 16.4 (mm)

3. Modern three-tube set, China, no-name.