Manly potentiometer knobs

A while back I was going to make some custom reupholster nails for a chair. The nail heads were going to be .45cal shell casings. Looks sick with black or dark brown leather. However I couldn’t get enough shell casings. So for a year or so they have been stashed away in a plastic bag in my storage room.

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Quick and easy Voltmeter with a Arduino and a TV.

A while back I stumbled on a small Arduino sketch that turns your Arduino into a Voltmeter. It uses a voltage divider on the ADC to lower the voltage/current and with some ones and zeros going around the AVR it spits out a voltage reading onto a parallel compatible LCD.

Since I was killing time the other day I thought I would try it out but I didn’t have a LCD on hand so I thought I would reverse engineer the code to use the Arduino TVout Library. Sure enough after about twenty or so minutes I got it to work correctly. Even had enough time to make it look fancy.

It’s very simple to setup. Pin A0 is the input with the voltage divider of 10K and 100K ohm. 10K is grounded and the 100K is the voltage input.

Digital Pins 9 and 7 are the sync and video lines for the composite video.


If you have a older TV that doesn’t have composite and has antenna jacks you could use this.


I’m not 100% sure but for PAL you just need to change the code from NTSC to PAL on the line TV.begin(NTSC,120,96); to TV.begin(PAL,120,96);. Also I think you would need to use Digital pin 12 instead of pins 7 and 9. When I was looking at the TVout library demos for NTSC and PAL side by side they look the same expect for the declaration of the TV.begin code.

Here is the code

DC Voltmeter
An Arduino DVM based on voltage divider concept
TVout port code by TCPMeta
Use a 1K resistor on pin 7
Use a 470 ohm resistor on Pin 9
Just follow the typical pinout for the TVout Library found everwhere on the net.
#include <TVout.h>
#include <fontALL.h>

TVout TV;
int analogInput = 0;
float vout = 0.0;
float vin = 0.0;
float R1 = 100000.0; // resistance of R1 (100K) -see text!
float R2 = 10000.0; // resistance of R2 (10K) – see text!
int value = 0;
void setup(){
pinMode(analogInput, INPUT);
TV.println(“// DC VOLTMETER //”);
void loop(){
// read the value at analog input
value = analogRead(analogInput);
vout = (value * 5.0) / 1024.0; // see text
vin = vout / (R2/(R1+R2));
if (vin<0.09) {
vin=0.0;//statement to quash undesired reading !
TV.println(9,85,”TVOut Port By TCPMeta”);

Now be sure to use the TVoutBeta1 from here. Also from tinkering out for better results is to messure the 10K and 100K resistors with a ohm meter and make it reflect on lines 16 and 17 to get a better zero out setting.

News 7/25/16

Today I finally received my circuit boards for my Analog O-Scope terminal. It’s a simple serial terminal that uses a analog O-scope as the video output. It also uses a PS/2 keyboard. I didn’t design it but just used the gerber files and had a run of boards made. I doubt I need all eleven of them but I could build them up and slap them on ebay.

The quality of the circuit boards are just fine and just awesome looking. The $28.00 price tag and long wait was worth it.


A while back for giggles I tossed together a Arduino based VoltMeter. Since I didn’t have a LCD handy I used the TVOut library and it gave that retro feel to it. The other day I started to think of a way to add a peek to peek voltage readout to my o-scope and I think this could work with the help of a LM8118. I tracked down the creator that made the “sketch” for the Arduino VoltMeter and he wants to see that changes I have made to the code so this Tuesday I’ll pullout the sketch I modified and give it a shot.

Theory of a Curve Tracer Revised

A while back I was going on a theory on a quick and simple Curve Tracer. Well I was dead wrong on a lot of it.

Lets talk about the Octopus circuit. It’s more of a passive component tester. A lot of scopes have this option built in. A real Curve Tracer is more geared towards Transistors, Diodes and Thryristors.

The TV CRT is not a good candidate. The CRT has to be a Electrostatic. Vintage TVs from the late 40s and up to the late 50s used Electrostatic CRTs. However you can find all over eBay Oscilloscope CRTs from ten bucks and upwards to eighty bucks.

To create a more of a real Curve Tracer I would check this out. The circuit uses a stair-step generator from a 555 timer and some Op Amps. However it looks like it can only do NPN transistors. Not to mention a scope that can do a X-Y function.

All-in-one lab update

I want to add a dedicated audible continuity tester. I have tried all sorts of ways and they don’t work or just make static sounds. I have found a solution and found a use for a PicAXE micro. It’s pretty simple and since it’s with a PicAXE you can make the tone anything you want pretty much. I don’t have a piezo or proper 8pin dip layout with the program I used to create that quick schematic.


Here is a example code for it.
main: sound C.2,(60)
pause 100
goto main

Another way I could tackle this since I plan to add a Function Generator is to add a simple signal tracer.

signal trace

I got this schematic from a YouTuber that rebuilds vacuum tube radios. It just blocks a DC signal and lets a AC signal pass by and inject a sine wave from the function generator you can use it like a continuity tester. Just have to add a amplified speaker to the speaker output.

Both possibilities are a low parts count and simple to build. As for the function generator I plan to use one of those XR-2206 kits.

News 7/14

Yesterday I went to RadioShack and bought a couple of things such as new desolder iron tips, prefboard and a few multimeter adapters.

I was also able to put the power supply for the All-in-one lab on a PCB.

Went to Harbor freight and bought new hand router bits since they were on sale. They even tossed in one of those cheap multimeters.
The router bits I already have are older then me and have seen better days. Not to mention the trimming bits do not have bearings and kick like a mule. Friday I plan to finally finish my router table and I can start on a few things that I’ve been needing a flush trim bit for.

Last night my wife told me the washing machine is on the fritz. Sure enough the dial to it has seen better days. The function to turn it on and off by push/pull on the knob isn’t working and it doesn’t stop at the spin cycle. I just find it funny it’s a Maytag and it uses GE and Whirlpool parts. A replacement price wise starts at $71.00 but typically used. A new one runs about $120.00 and up. It’s not bad but since my electric bill is over $300.00 for this month I can’t afford it.

Yep, my electric bill is $305.67 this month. Used about 2,500KW because of the A/C in this apartment. The A/C is 26 years old and we have had issues with it since we moved in five years ago. The other day I decided to clean out the condenser coil myself with some coil cleaner since I had half a can left from when I cleaned my window unit. The coil is so old that the fins just crumble when you touch it. I had the maintenance guy come by yesterday and I told him about it once again and told him what I have done. Cleaned the coil once every few months, swapped out my thermostat to a digital and even checked the coolant myself. He then took pictures of the coil and said all he can do is show the property manager. I should of gave him a copy of my electric bill to show the property manager. In the meantime I have set rules and guidelines with the power usage. At midnight everything must be off, I have the thermostat set to raise the tempt to 80 at night and around 10 in the morning go back to 77. I got all of the bedroom doors open with a fan in the hallway to pull cool air from the master since I have a window unit in there. The crappy thing is in Florida the landlord does not have to provide A/C but they have to provide heat. I know, very stupid. Yet as a tenant the dwelling must be maintained from mold and mildew. If there is no A/C then mold and mildew will grow. So I would have to open all of my windows and run fans to keep things a bit cooler if the A/C decides to fully breakdown. Now I am not a A/C professional but what if only the condenser coil was changed out. Would this be a solution or would it be a waste of time? My advise is don’t rent…

Printers – A love and hate relationship

Back when printers were cheap enough for the average consumer could buy people would make several backups to floppy disk and a printed hard copy.
I remember reading A+ certification books that had two or three chapters on just printers alone.
When printers were starting to decline in sales for the home user companies started to toss together multi-function devices that print, scan and fax. Things couldn’t get better but there is a major downside.
This to me was very noticeable when Windows Vista veered it’s ugly head. My mother had bought a Compaq that had XP but was offered a free Vista upgrade from HP/Compaq. When she bought the computer she also bought a brand new Lexmark all-in-one multi function printer. When she had me upgrade the system to Vista it was printer suicide. Thinking there was a driver or let alone a driver on the way for the printer since it is still new and Lexmark still supported it. Nope, wasn’t Vista compatible and Lexmark stated there will be no new driver and told everyone to buy a new printer. By this time I was getting calls from people asking how to get their printers working in Vista and so forth. I was going crazy at this point.

To make matters worse companies such as Kodak made great printers with one evil intent to keep getting money from you. There was even a class-action lawsuit on this. I had one of these all-in-one printers, I forgot the model though. What would happen was when a user inserted a new ink cartage the printer would put a time stamp on some little chip on the cartage so after thirty days the printer would say it’s empty. So if you printed say two papers in the whole thirty days then you’re screwed.
Other companies also block out other functions when you’re real low or out of ink. So if you needed to only send a outgoing fax you need ink. If you wanted to scan a photo to the computer you need ink. These are not failsafe but intended for you to buy more ink. It’s not hard to program the microcontroller to tell it to not print a scanned document or print received fax when it’s out of ink.

Refilling your ink isn’t as easy as it use to be. There are kits you can buy that is cheaper in the long run to refill your old cartage but now there are basically real-time clocks added to the cartage that will stop you. So if the cartage is a year old the printer will think the ink is dried up. Also the sad thing is you can still buy at OfficeDepot Apple DMP ink ribbons but HP 22 and 56 are not carried anymore.

If you attend to print a lot or even a little your best bet is to invest in a Laser Printer. They’re are pros and cons but in my opinion it’s worth it.
The toner costs about $50.00 and up but you can get anywhere from 500 to 1000 prints from one cartage. They’re huge and take up a ton of space, not to mention mostly print in monochrome. However it can sit there for a year or more and still print fine. They’re cross platform so if you have a Mac, PC and a Linux box then chances are it is supported since Laser printers are favored in the business world. You can even upgrade the memory and add a print server card to make the printer function on a local network so if you some how end up with a OS that doesn’t supported it you can still use it though the network ether by uploading the document via HTTP on the print server and printing it from there or from another computer with simple file sharing. There are color laser printers but they are costly but think about it in the long run. Do you really need color prints? If you want photos done there are places you can take a memory card to and have professionally printed photos created. Doesn’t cost much and still cheaper then ink a cartage. For scanning I would try and find a old flatbed scanner. However I would research and make sure it is supported or if anyone had made any 3rd party drivers. Most flatbed scanners vanished around the induction of Windows XP. However if you can find one that is Linux compatible then you can use a print server to host it. For faxing there are a few ways to do this. There are some faxing services that will let you send a Fax from your computer. Basically it’s a email that is converted to a fax and spits out a fax on the other end. You could go to a thrift store and find a fax machine for a couple of bucks. I myself use to have home server that had a old 56K data/fax modem that I can send and receive faxes. If anything there’s the UPS store and FedEx.

In general printers are cheap and at times the printer is cheaper then the ink. You could even waste money on keeping the ink flowing and out of nowhere they just die.

For a electronic hobbyist these modern printers suck for harvesting parts from. At one time they used stepper motors, digital logic, motor controllers and some beefy mechanical parts. Now it’s mostly plastic, use typical brushed DC motors with digital encoder wheels and sensors. SMD parts on the controller board and a micro controller that uses a special reader/writer that costs a couple grand. A laser printer however still uses stepper motors and motor controllers. However a laser printer itself is a awesome tool for the electronic hobbyist. You can make printed circuit boards and control panel bezels with it to just name a couple of things.

A friend gave me a Brother HL-1850 Laser printer and he said the toner has been in there for years and the casing is a bit discolored. I hooked it up to my laptop last night and Debian almost got it ready automatically so I tried out the CUPs server by pointing my web browser to http://localhost:631
and just added the printer manually. Works a treat and prints very nice. I have to say this is one of the nicest laser printers I’ve had yet. All because of this printer it made me think how typical consumer goods have gone down hill and how companies like to stick it to ya.

Laptop buyers beware.

When you decide to buy one of those “budget” Laptops from Walmart or even Bestbuy you will find in my opinion some unsettling things about the hardware. The description is vague and if there is a floor model to look at it is still vague because hardware manufactures like to use generic names for hardware. For a example in device manager it will list the video has “Intel HD Graphics” and the chipset would list as “Intel”.

When you read up on the specs from the manufacturer they give better detail but not much better then what you find in Device Manager.

When I switched over my Acer ES1-512 to Linux I found ouet t it is listing the hardware as a Atom Processor Z36xxx/Z37xxx SeriesAtom Processor Z36xxx/Z37xxx Series. Although the system really has a Intel Celeron N2840. Odd thing is Windows saw the CPU as a quad core but Linux sees it as a dual core. Sure enough it is a dual core and uses a crappy chipset.

I’m not 100% sure if Linux is using the correct kernel modules or the chipset is based off of the Atom z36/z37 series. It’s a bit of a headache. I guess I need to crack open the laptop and look and see what I really have and check up on some datasheets.

Just beware, a cheap laptop is in fact cheap hardware. Yet even expensive laptops can also be junk. This is when you start researching everything you can about a laptop before you toss cash at one.

Acer es1-512 and Linux

My wife gave me a Acer ES1-512 a few months ago. It had Windows 8.1 and I tried to cope with it and wanted to bash my head in each time I wanted to do something with it but Windows would deny me. So I installed Debian 8 (Jessie) Linux on it. Runs quite well, I need to tweak a few things but other then that it runs out of the box. I had to disable the Secure Boot option and now I’m trying to unlock the EFI system to access the “Hidden Page” that will let me change some systems settings that the typical settings doesn’t have options for. Such as the video ram and a few other features.

Software wise I ended up installing everything that the Debian installer offers. I’m using GDM3, Awesome WM and Cool-Retro-Term. To minimize the window count I’m using Screen for the multitasking.