Cristiano Maker

I'm building and studying metal detectors for more than 15 years and learned a lot of things both from my curiosity and experimentation and also a lot on Geotech forums and so, I've decided to write an eBook about the Metal Detectors Technology without entering in complex technical subjects dedicated for all the metal detectorists that want to know better how their machines work and take advantage of that while searching for treasure or prospecting precious metals. You can download it in Amazon for a very affordable price. Here are the links: English version (Metal Detectors Made Simple: The Technology Behind Treasure Hunt):  https://www.amazon.com/dp/B0FT2173T3 Portuguese version (Detectores de Metais Descomplicados: A Tecnologia por trás da caça aos Tesouros):  https://www.amazon.com.br/dp/B0FSC448WC Any suggestions, leave your comments!

 After some objects made successfully with my first vacuum forming machine (check it here ) I needed to build a bigger one (50cm x 50cm) table. I've also built a custom "oven" to heat the plastic, it is just a wooden box with the internal walls covered with aluminum foil and a heater element in the middle that I took from an electric grill. This was also the first time I have used ABS plastic, that is much more impact resistant than the previous one (Polystyrene). I'm still using the vacuum cleaner as the vacuum source, but my next plan is to store the vacuum in a air cylinder so I can evacuate the air faster preventing failed formings. You can see a short video of the machine here: If you are interested in making a machine like this, please watch my other videos on youtube related to it. You can also buy the eBook I wrote with all the steps required to make a vacuum forming machine from scratch with easily available tools and materials. Check the eBook landing page: ...

 I have made some metal detectors, both VLF and PI. Until now, one of my favorite is the Minipulse Plus Beach as known as MPP Beach. It is a Pulse Induction detector specially designed to work in the beaches but you can tune it to use in many other situations, like finding Gold nuggets. If you are interested in the project, please check the Geotech Forums, in my opinio, the best forum about metal detectors:  https://www.geotech1.com/forums/forum/projects/minipulse-plus/14902-mpp-beach-rev-e Below, are 2 videos I have testing the detector I've build, firt, with a Spider web coil and latelly with a simple mono coil with 3m shield tape. https://youtube.com/shorts/ksGzeMP_x0I?si=OkjFHkC09U5LKZKO The best result was found using the mono loop coil shielded with the 3M tape. If you have already made this detector, please share in the comments your results with it!

  There are several ways of storing rocks and minerals specimens. Some prefer to have them visible, other prefer to have them secured in boxes. Personally, I prefer to have them stored in a box, so they don't get dirty with dust, so I decided to build a simple wooden box. It is a simple rectangular box with small boxes inside like drawers that are pulled from top. Dimensions of the main box are 40cm length x 20cm wide x 25cm height. There is space for about 4 drawers inside. I have organized the smaller specimens into paper boxes, although the larger specimens are loose. You can see a small video of how it works to open and pull the inner drawers:  https://www.youtube.com/shorts/LhDBVJ7s5Vk I have used this style of box to store minerals but I can be used for any other kind of collectible.

 I have an old kerosene pressure lamp, a Ditmar Maxim 520, but when I bought it, it come with some little cracks in the tank, so the first time I tried to turn it on, I noticed the kesorene leaking at the bottom. Searching in some forums for a possible solution, I have found a simple one: filling the cracks with tin solder. Here is a step by step if you also need to repair your pressure lamps: 1 - Identify all the cracks. 2 - With a dremel, open the cracks exposing the internal metal (make sure your tank is empty and dry of kerosene). 3 - With a torch and tin solder (the one used in electronics), fill the exposed metal crack with it. 4 - Test the pressure before adding kerosene. 5 - If the pressure keeps ok, you are ready to use your lamp again! Here is a small Youtube short video of the process: https://www.youtube.com/shorts/0442OXCgXjc  This is the final repaired tank:

 One of my hobbies is to build electronics projects, like metal detectors for treasure hunting. Usually electronics boards are hold inside a plastic or metal box. There both in the market, but usually they are not so cheap. One solution I thought about, was to build my own boxes using aluminum sheet as it is a soft metal. Although aluminum is soft, for the thickness I want to use (2mm) it is not so easy to bend it by hand, so I searched a bit how to make a tool to bend the metal with the less effort possible and with good results at the end, I came up with this, using only 3 pieces of wood, 2 screws with bolts and 2 hinges: This is known as a sheet metal brake, mine is simple, made of pine wood but I recommend you to use harder woods, specially if you need to bend metals harder tha aluminum. I think you can replicate one easily just by looking at the pictures above, so I'm not provinding any measurements but if you need, please write a comment below. For different sizes or formats ...

 As I work almost all day sitting down, there comes a time in the day when I get fed up of staying in that position for so long. So, I decided to make a simple and small desk that I can put on top of my main table and this is the result: This way I can simply add or remove the small table at any time I want to work standing up. Obviously there are in the market beautiful and comfortable standing desks, but at least here in Brazil, they are quite expensive so I decided to make mine with a few pieces of wood and 4 screws!

There is an amazing device to do exercises at home named "Power Twister" or "Power Crusher". I used it since my 10 years old. Below, there are some pictures with good exercises to do with it. The guide is in Portuguese but the images tell by themselves.

In my opinion, the Republic P-47 Thunderbolt is one of the most amazing planes of WWII. Some time ago, I found some interesting videos on Youtube showing how to fly this plane:

This is my homemade vacuum forming machine first try. I want to make a metal detector coil housing but I failed at the first time. May be due to using a too thick plastic (2mm polystyrene) or not enough temperature. The vacuum is obtained from a small vacuum cleaner (1400W) Here are some pictures of the device and a video. Next time I will try with a thinner plastic or other type (ABS). Part 2 - After some fails, the success! Well, today I will talk about the second try. I'm using the same type of plastic - polystyrene, 2mm but now I have a thermometer so I can measure it's temperature. I also added some screws to the frame, so I can prevent the plastic sheet from moving with the heat (because of expansion / contraction) and finally I got a good result as you can see below: I kept the plastic in the oven until it reached about 150 degrees celsius at the center of the sheet. Almost perfect. Not 100% because it seems I moved slightly the form out of place and it is not centered. ...

Some days ago, I was on the internet searching for old amateur radio projects and I've found a website that contains a lot of old magazines (  https://worldradiohistory.com/Archive-Short-Wave-Television/30s/ ) with exactly what I wanted - the only problem was they are so many, that I was no patience to download one by one, so, I decided to use some of my programming skills to help me, by making a simple python webscraping script, using the BeautifulSoup library. If you want to learn how I did it, please check my YouTube video below:

 Today, I made a simple video demonstrating how the control grid of a vacuum tube triode may work. Essentially, the purpose of a control grid, is to control the flow of electrons from the cathode to the anode of a vacuum tube. So, im my experiment, I put my ammeter in series with the B+ and the tube plate and applied a positive charge from a 9v battery and then I inverted the battery polarity, applying a negative charge. In the first case, It is possible to see the current flow increasing, while in the second case, the current practically doesn't flow anymore. You can see this simple experiment in the YouTube video below: For this experiment I used an early type 30 tube, a 1.5v battery and a 90v stack of 10 * 9v batteries and a couple of wires. Hope you like!

 I live in an old house that has no grounding system. As I do many projects using considerable voltages, like vacuum tube amplifiers, I need at least a grounded wall socket for my own security and the security of my devices. So, as my house is rented, I don't want to request someone to make a full/proper ground installation for the entire house. Instead, I created my own grounded socket. Fortunately, the house as a backyard, so I bought a copper grounding rod and buried it into the backyard and then I took a thick wire from it to the inside of the house and made a connection to the ground pin of a "female" socket and I'm using it for my projects. Below, there is a simple video showing the efficiency of that system I made: You you have a similar situation as mine, you can do something similar.

 Maybe you don't know, but you can use a car wiper motor to power your low speed / high torque project. For example, I used this kind of motor to power a ball mill I made some time ago. All you need is a used wiper motor, a computer ATX power supply and 2 wires. The first step is to find what is the low speed connection of your motor. Usually, it is a connection labelled with "53". If you can't find this in your motor, please take a search on the Internet about that for your specific motor brand / model (you can search also by the vehicle brand and model from which you got the motor). Then, as the 12volt supply, we will use any yellow wire from the power supply, and for the negative (ground) you may use any black one. Is simple as that, just connect a yellow from the power supply to the low speed connection of the motor (53 code) and the black wire to the ground connection (this could be simply the any metallic part of the motor). Please take also a look the the YouTu...

 One of my passions are antiques, specially if they have some engineering or electronics envolved. Since I was a child, I had contact with antiques from my grandparents, and one of the things I remember is an old kerosene pressure stove. Some time ago, I decided to buy one, just for decoration, but I also love to keep things working, if possible, so, I decided to turn it on, and made a simple tutorial on how to start it. I made a vide that is available on YouTube, please check it below: I added some subtitles to the video so you could understand better, but I'm also going to write it here: 1 - Put some kerosene in the tank 2 - Fill the small cup below the head with alcohol (+ 90% is good) 3 - Light up the alcohol and let the head warm and start vaporizing the kerosene 4 - Once you feel the pressure increase, give some pumping to help it increase even more 5 - The kerosene vapor will light by itself with a beautiful blue flame (if you need more pressure, pump it more, for less, rele...

 After my first tube amp , I decided to try a battery powered one. There is not a lot of information about guitar tube battery powered amps on internet, but I found some resources. My search began on YouTube and I found a video of a guy that wrote the schematic link in his video description here . I just followed it, mounted the components of the amp (all point-to-point wired) inside a large tin can and used my small 6 inch speaker connected to it. The amp is powered by 10 x 9v batteries ( for tube plates ), one 1.5v battery ( for tube filaments ) and 3 x 1.5v batteries in series, providing 4.5v of negative bias. The tubes used, are one 1Q5GT and two 1T4, early used in battery powered radio receivers. It has just two controls - volume and tone. Here is the schematic: Here is the power supply schematic: And here, the built amp: Check out my videos on YouTube of this amp playing a song from my computer and also a song from my guitar: Hope you enjoy and if you plan to make an amp li...

 One of my favorite electronics projects are metal detectors. I'm trying to build some famous and more complex detectors like the TGSL (VLF) and the Delta Pulse (PI) but I also decided to try a very simple approach - using an Arduino and a few electronic components. As I also work with programming, it was very interesting to join the 2 areas (electronics and IT). The detector works as an "educational" purpose as it detects a large coin at about a 3-4 centimeters distance from the coil while professional detectors can detect objects at a very larger distance, although it can be a great opportunity to learn more about how metal detectors work (in this case using the Pulse Induction technology). I found this project in a YouTube video, and it is not created by me but I'm sharing it with you. In my test, I replaced the LED with a piezo buzzer, so, the components I used were: - 1x Arduino UNO - 1x protoboard (optional as you can mount the components any other way) - 2x 220...

 This is one of the most essential safety devices you must have if you work with electronics. Not only for the safety of the device you are making/troubleshooting but also for you and your electric installation. It is a famous device - the light bulb current limiter also know as dim bulb . The construction is very simple, that's only a high wattage bulb connected in series between your device and the wall. Here is the schematic: I recommend to use a high wattage filament bulb, like a 150w or 200w, usually the rule is to use a bulb with a higher power than the device do be tested. Please not that the wattage must be the real and not the "equivalent" as we find in modern fluorescent lamps. It is mainly used as a "detector" for short circuits: if your device has a short it will draw a lot of current from the mains and the bulb will be as bright as it can, limiting the current because itself will convert the energy into light and hot. If the device has no shorts, th...

Since I was a child, I love vacuum tube/valve stuff, like old radios and guitar amplifiers, so I decided to build my own guitar amp. I have made a Fender 5f1 model, all from scratch. I made it as a "head" because I want to try different speakers along the time, and the speaker I have at the build time is not a very good one but it does the job. Before I started the build, I read a lot of things about vacuum tubes so I can be more comfortable with the build. As you also may know, tube circuits use generally high voltages (around 650v in this case) so it may be dangerous if you don't know well what you are doing. There is a lot of information on the internet about this specific tube amp model. If you plan to build something like this, I recommend you visit this page  and watch a lot of videos on YouTube about tube amp build and repair (I recommend 2 channels: Uncle Doug and D-lab Electronics). Below are the layout and schematic I used for the build. They are the original Fe...