A fine-spot welder is one of the few equipment where building yourself is cheaper than buying. There are already published a lot of DIY spot welders, this one has some unique features:
It can be used in 2 welding applications: opposed and series configuration.
The construction is kept very simple.
Accurate electrode force adjustment.
It has a solid electrode holder, made of a radiator earthing clamp.
An Arduino microcontroller is used to set the weld time accurately.
Creates a double pulse which improves clamping.
The current can be reduced for welding sensitive parts.
DIY battery tab resistance fine-spot welder - [Link]
by sajjad Haidar @ edn.com:
Power supplies with adjustable DC output ranging from 0V to 30V or 60V are on the market. Above 60V, there are not many. This Design Idea offers a solution.
There are many fixed voltage switching mode power supplies (SMPS) available, and connecting several in series can give us a higher fixed voltage. To obtain an adjustable output either from a SMPS or conventional transformer based supply, one needs to use a linear regulator or a switched mode buck converter. For a buck converter, a MOSFET or an IGBT can be used as a switching element.
Usually, for a high side switch, an IC with bootsrap operation or a pulse transformer is used. There are few photovoltaic couplers available to drive MOSFETs. As they do not provide much current to charge the gate capacitance quickly, these photovoltaic couplers are mainly used to drive low frequency MOSFET switches, such as solid state relays.
Variable HV power supply employs photovoltaic optocoupler - [Link]
Tom Cousins of DOAYEE made this DIY nixie tube clock:
Below is the schematic for the project, as you can see I’m using 6 IN12 nixie tubes, each with it’s own 74141 nixie tube driver. These drivers are great! They simply connect directly to the nixies and display whatever 4 bit binary number you give them (if you give them anything above 9 they blank the display – hence why I use the number 10 in my code to blank the nixies). Because they take in a simple 4 bit binary number, I can hook them directly up to some shift registers to drive them, in my case I used 3 74HC595 shift registers (available everywhere), because they can be “daisy chained” together, meaning in the code I only have to write one 24 bit binary number and it will display all 6 numbers on the nixies. Though in reality I split them up into pairs and write three 8 bit binary numbers.
Nixie tube clock - [Link]
The amplifier is based on the 12AU7 valve (part number ECC82 in Europe). The schematic came from here, it’s a nice kit, but lacked a power supply and the layout wasn’t quite what we needed for kits in TinkerSoc. I added a LDO 12v regulated power supply, an input volume control pot and kept the design single layered (with one jump). The final schematic can be viewed here
Tube Amplifier - [Link]
If you are doing any electrical work, one of these Non Contact Voltage Test Pens can be quite handy. Just touch the wire that you want to make sure isn’t live and check that the tester doesn’t beep and start flashing. This test pen is on all the time monitoring for AC between 90V and 1000 V. I would have preferred the device to have an on/off switch which would allow the battery to last even longer but I guess they figured that the 1.5 year life that they rate this for when in standby was good enough. This impressive life is because they got the current draw down to under 10 micro amps! Even when operating it only draws a handful of milli amps.
Non Contact Voltage Test Pen Teardown - [Link]
Jan Rychter @ jan.rychter.com designed his own Nixie power supply that except the high voltage has two voltage outputs to power the logic circuitry, he writes:
This project is a HVPSU (High-Voltage Power Supply) that generates up to 220V from a 12V input. In addition to that, it also provides 2*Vout (so, up to 440V, for dekatrons), and two outputs for powering digital logic: 5V and 3.3V. The primary HV boost circuit reaches 88% efficiency when going from 12V to 185V at 55mA, with a 3% output ripple.
I designed it because I couldn’t find anything that would make sense for my Nixie projects. There are plenty of tiny power supply modules available on eBay, but most of them end up being impractical: no 3.3V (for my microcontroller) and 5V (for my 74141 nixie drivers), no mounting holes, no >400V output for powering dekatrons. Some supplies make a token gesture towards practicality by sticking a 7805 on the same board, but you quickly find out that the current draw of 6×74141 is enough to require a large heat sink on a 12V-powered 7805 (one 74141 consumes 12.5mA!). This means that instead of a single-board power supply you end up routing your input power all over the place, implementing your power supply in several places.
High Voltage Power Supply for Nixie Tube Projects - [Link]
rwilsford07 @ instructables.com:
A boost converter works in two stages, ON and OFF. In the ON stage the Semi-conductive Switch is conducting and current builds up in the inductor producing an electromagnetic field, this field stores energy. In the OFF stage the Semi-conductive Switch does not conduct and the electromagnetic field collapses. When the field collapses the energy stored in it can not escape through the Semi-conductive Switch so it goes through the diode and into the load/Capacitor at a much higher voltage. This happens several thousand times a second via the pulses from the NE555 Timer Chip and the result is being able to charge a high voltage capacitor from a low voltage source. Below is some aid for those of you who do not know electronics well.
DC-DC HV Boost Converter - [Link]
Nixie tubes need about ~180Vdc to light up and thus on most devices a DC-DC converter is needed. We designed here a simple DC-DC switching regulator capable of powering most of Nixie tubes.
The module is based on the MAX1771 Step-Up DC-DC Controller. This controller works up to 300kHz switching frequency and that allows the usage of miniature surface mount components. It accepts an input voltage from 2 to 16.5V and the output is factory configured to 12V. In this module the output voltage is configured higher at ~180Vdc using external resistors and a potentiometer.
HV Nixie DC-DC Power Supply - [Link]
Andrea Biffi build a nice vertical nixie clock using ATmega8 mcu. He writes:
After the success of my first nixie clock made out from a rosewood block, I decided to lose no time and to carry on with the next one. As some of you guys already know, or imagine, lately I’m indeed a little bit addicted to nixie-mania. I’ve bought many nixie tubes on eBay, and I experienced in electronics so to build my own high voltage power supply and then the ultimate nixie clock circuit. Digits for this clock are nice rounded and fully transparent IN-4 tubes, the same I used in the first model, but as I previously announced, I aligned them vertically, so to read from top to bottom hours, minutes, and seconds. Indeed you will see the undeniable influence of Max Pierson’s vertical clock. I guide you now through the full process to make your own unique nixie clock.
Vintage style nixie wall clock - [Link]
I always wanted a spot welder, so I decided to built one. I wanted to build a capacitance discharge one but I couldnt afford for the capacitors at this time. So this is a controller for a dual pulse spot welder with some few extras:
– It has a zero cross detector. You could power the transformer at zero cross or dim the transformer if you like
– The transformer is triac controlled
– It has an hd44780 interface
– An spi interface for single thermocouple
– Peak detector of a current transformer
– Isolated foot switch
– Voltage monitor with opmaps
– An attempt to sense when the user tries to weld
– Single rotary switch for operation and single rotary encoder for setting up
MCU Controlled Spot Welder - [Link]