New Resistance Substitution box


I recently bought a new Resistance Substitution box off Amazon. It is clearly a hobbyist grade piece of equipment, but it only cost 35 dollars. I used two meters and a power supply to get a accurate measurements of the resistors in the unit.

The substitution box was more accurate then I expected it to be, however it was not in the range specified by the manufacture.




set resistance voltage (v) current (mA) resistance percent accurate
set resistancevoltage (v)current (mA)resistancepercent accurate
1 0.2923 251.1 1.16E+000 16.41%
2 0.546 251.1 2.17E+000 8.72%
3 0.8018 252.3 3.18E+000 5.93%
4 1.0515 252.1 4.17E+000 4.27%
10 2.539 251.9 1.01E+001 0.79%
20 4.9877 251.9 1.98E+001 -1.00%
30 7.386 252.1 2.93E+001 -2.34%
40 9.665 251.9 3.84E+001 -4.08%
100 23.12 251 9.21E+001 -7.89%
200 18.27 93.6 1.95E+002 -2.40%
300 18.332 62.5 2.93E+002 -2.23%
400 18.361 46.7 3.93E+002 -1.71%
1000 28.50 28.94 9.85E+002 -1.52%
2000 28.53 14.36 1.99E+003 -0.66%
3000 28.54 9.54 2.99E+003 -0.28%
4000 28.55 7.19 3.97E+003 -0.73%
10000 28.56 2.86 9.99E+003 -0.14%
20000 28.56 1.43 2.00E+004 -0.14%
30000 28.56 0.952 3.00E+004 0.00%
40000 28.49 0.716 3.98E+004 -0.52%
100000 28.53 0.2861 9.97E+004 -0.28%
200000 28.53 0.1444 1.98E+005 -1.21%
300000 28.56 0.0974 2.93E+005 -2.26%
400000 28.56 0.0735 3.89E+005 -2.86%
1000000 28.56 0.0307 9.30E+005 -6.97%
2000000 28.56 0.0166 1.72E+006 -13.98%
3000000 28.56 0.0118 2.42E+006 -19.32%
4000000 28.56 0.0096 2.98E+006 -25.63%


I opened it up to see what it looked like on the inside.  I thought the build quality was good for such an inexpensive device. Fasteners go though the front plate, to a PCB, and then into a threaded cylinder. Screws also enter the threaded cylinders from the other side, though the case.IMG_0807


The PCB is straight forward. There is simply an array of switches and there the corresponding resistors are right beside the switches.


I burned the 100 ohm resistor on this board, when I was not paying attention. (pure negligence)


The high value resistors are a bit different. It appears two resistors are placed in parallel. This looks goofy to say the least.



The other side of the board has a nice green color to it. It is clear that this is a single sided board, which I don’t see to often anymore. Large though-hole components make single sided board possible.


I can’t be certain, but it looks like this board was hand soldered. The amount of solder, and way it sticks to the pads leads me to think it was not wave soldered. I can defiantly see finger prints on the finish of the board.

IMG_0799This will be a very useful piece of equipment when I start testing DC-DC converters, and need an constant sink for my test supplies.



Site hosting, and Domain registration, and analytics

This blog has been online for around a year now, and I thought it would be a good time to share my thoughts, and experience. Earlier today the site was down, because I forgot to renew the hosting plan. I remembered to renew the domain name (, but the hosting plan slipped my mind.

So far I have no complaints related to namecheap’s  hosting or registration. Their website is slightly confusing, but they have been fair. I pay $30 for the registration, and $38 for the hosting. I could have gotten a .com for less but I like the .io (it helps me feel hip and trendy).

I have been using google analytics to track sessions, and usage over time. I suspect some of my CS friends would be irked to know I let google track them.



There are 4,693 sessions which is much higher then I expected. The average user looks at 1.2 pages per session, and spend a minute and 24 seconds.

I enjoy looking at the map, and thinking about all the countries that have visited my website.


The counties that have the most sessions are the US followed by Russia and China. states_country



Every state in the United States have visited my page. Kentucky (my home state) followed by California are the top 2 states.  stats_map_US



Below is a listing of the most mobile deices that have been on my page. Iphones lead this group by a massive margin.



The below data shows how many uses spend time ranges of time. I have a total of 4,693 sessions and 4,039 of those sessions are less then 10 seconds.stats_time


Google also understands acquisitions (How users got to my page). Most of my sessions are bots. Users that find my page (organically) through google search, spend an average of 6 and 21 seconds. These  356 are probably real people.


The google analytics tool are very complex and do many things. I don’t understand or use all of them, but this has been a brief overview of the google analytic tools I use.

Jeep (Old). Timing belt, and valve cover


Timing Belt Cove

The timing belt connected the camshaft and crankshaft. The crankshaft rotates twice, for every one rotation of the camshaft. The cam and crank shaft are still deep in the engine.

The timing belt. The large gear is attached to the camshaft, and the small gear is connected to the crankshaft.
The dots must be aligned, so the camshaft and crankshaft are synchronized.

The chain was pretty easy to take off. Noticing these dots is important for alignment.

Here is an older image of engine with the valve cover on.



IMG_0438  Once the valve cover is removed the push rods, rocker arms, and the valves. There are lifters on the camshaft, that push up on the push rods,  and this causes the rocker arm to lower. This pushes the valve down, opening the valve.

The rocker arm is a seesaw. When the push rod goes up the the valve goes down.

0601_ctrp_01_z+rocker_arms+diagram_view pedestal-rocker-arm


Above are two diagrams that show the how camshaft uses the push rod, and rocker arm to open ans close the valves. Each cylinder has two valves one is an intake valve, and the other is an exhaust valve. IMG_0436

dirt bike carburetor (yamaha ttr 125)

We have a Yamaha TTR 125 dirt bike, and the carburetor leaks gas continuously. Rather then trying to rebuild the carb, we planned on just replacing it. New aftermarket replacements are very inexpensive (around $45). I don’t normally work on dirt bike fuel systems, so this was kind of new for me.

The new shiny carb

It was relatively simple to replace the carburetor. It took a second to insert the throttle, and choke cables.

Old carburetor ready for disassembly

Below are two diagrams that show the internal workings of a carburetor.



I took the carburetor apart just to see how it works. While it was in pieces, I snapped some photographs.

The float bowl is removed, and the two floats are visible


The throttle slide, and spring


totally disassembled

Ham radio

I now hold a amateur radio technicians  license. My call sign is KM4OGC, and it wont expire for 10 years.  This allows me to transmit on the 10 meter, 6 meter, 2 meter, 70 cm , 33 cm, and the 23 cm bands.

Amateur radio bands, color coded.

I am going to have to remember my call sign KM4OGC  (Kilo Mike 4 Oscar Golf Charlie). I have a radio ordered on and on the way. It is a baofeng dual band 2 meter and 70 cm.  I am exited for it to arrive, and start contacting repeaters.

The local radio club, w4nja, was very friendly, and made it very easy to take the exam.

Jeep (old) Harmonic balancer, water pump, and thermosat with housing

The front of the engine still has three things we need to remove on it. The harmonic balancer is a special weight, that dampens the force between power strokes. The engine is a straight 6, and it is 4 stroke. Half the time the engine is on one power stroke, and the other half the time the engine has 2 power strokes (slight simplification).


The harmonic balancer is designed to compensate for some of the harmonics introduced by the crack shaft.


Front of the engine



Brother removing the harmonic balancer
In front of the balancer is a pulley held on by three bolts. It is the drive pulley.

The harmonic balancer puller uses 3, or 2 bolts to attach to the puller. It also has a central thread. Tightening the central thread on the puller loads the tread in compression, which loads the bolts in tension, until the balancer is pulled off.

harmonic balancer puller in action



Normal looking thermostat. Two pieces of metal and a spring




When the engine reaches a specified temperature the thermostat is designed to open letting coolant though the system. Engines run better when they warm up, and thermostats are a simple tool for letting engines warm up quickly and not over heat.

The thermostat housing (I always called it the goose neck) was relative easy for us to take off. It was incredibly rusty inside the housing. However, I believe the thermostat we removed worked fine, but we replaced it anyway.

Now the balancer and the thermostat housing are gone, the water pump is next.


The water pump is being removed from the front of the engine.

The water pump is belt driven. The four bolts on the front of the pump are designed to connect a fan, and pulley. We replaced the water pump before reinstalling the engine.


Passenger side of the engine


After the fuel pump is removed, a small section of the cam shaft is visible though the mounting hole.
The oil filter is orange, the distributor is blue, the goldish cylinder with the hose is a mechanical fuel pump

The fuel pump is driven by a special lobe the cam shaft,


A idle engine speed is around 800 rpm (revolution per minute). That is 13.33, revolutions per second.  That is a revolution every 75.19 milliseconds (1/13.33) seconds.

Every revolution, all the pistons stroke 2 times, and the pistons are on a 4 stroke cycle. The piston is able to traverse the length of the cylinder in 37.6 milliseconds, and that is at idle.

At an rpm of 4800 the piston complete a stroke in 6.2 milliseconds. That is very fast for a mechanical system, but that impressive to computer and electrical people it is kind of slow.


canUSB version 0.2

I have finally populated the canUSB boards, and they are working very well.


There is an issue with the SPI clock pin. It was suppose to correct in this board version, however I must have missed it. A small piece of blue wire gets these boards working.


The url on the board doesn’t work

Tried to make the Board URL to work, but WordPress had difficulty with the “/” character.






I am very happy switching the USB connector to a type B, from the Mini USB connector. The Mini USB connector was very difficult for me to solder with an iron.

Rigol DS1102E

Above is a screenshot of the can bus in action. The 11 bit identifier is 771, and there are zero data bytes. The messages are sent and received successfully.

USBtin (new boards in)

There is a new version of the the USBtin (USBcan) board. I have not populated it yet. I added another decoupling capacitor to  to stabilize the MCP2515, I correct the SPI clock line, and switched the USB connector from micro B to  standard B.

CAD of the top of the board
Image of the top of the board. (not populated)


CAD of the bottom of the board.
Image of the bottom of the board. (not populated)







I look forward seeing if I fixed the issues with the first version. I will not know if I fixed all the old issues until the board is populated and tested.




Jeep CJ-7 (Old) Manifolds

For us it was a big deal to take the intake and exhaust manifolds off. Before we could start taking the manifolds off we had to remove the vacuum inlet. Older engines use the vacuum presser to control many things, from power breaks to distributor advance. 

Vacuum hoses can be seen on the intake manifold
Vacuum hoses can be seen on the intake manifold

At the time we were very concerned about the number of vacuum lines around the engine.


Me and my brother thinking.

After the all the vacuum lines were off and documented, we started to remove the intake manifold. The bolts were in good shape, and it was not too difficult.

IMG_0340The exhast manifold was more difficult to remove because of all the rust around it. The heat the exhaust manifold experiences make it rust a lot more. I do not recall what the rail above each inlet does. (If someone on the internet knows please let me know).



That is what a jeep CJ7 4.2 Liter engine looks like with both manifolds removed. We put the valve cover back on to keep it clean. It looks like we put the bolts back in the block to avoid losing them. Next we will pull the harmonic balancer and take the water pump off.