DIY CIRCUITS ELECTRONICS

ultraviolet exposure device i built few months ago. it is controled by an arduino pro mini and has a 7 segment display to show the set and remaining exposure time. it uses ultraviolet leds(49 total)bought cheap from ebay. you can wire the arduino and the rest components using the diagram below.this way i made it too.you can connect any common cathode 7 segment display as long as you know witch pin is the segment shown in the diagram.or you can find it by applying about 3volts to each pin to see witch segment lits and write it down.(as i did)or downloading its diagram if exists.. then programm the arduino with the code given in the link below.you can skip the circuit with the mosfet and the optocoupler and connect a 5 volt relay as shown in the diagram(relay output & ground) to controll the leds. if you liked this project please subscribe to my channel for more future projects.... arduino code : https://drive.google.com/open?id=1SK-jNM7jZIcx-jIN8e3rleN_-12L9IQG

mini teardown of a working very old cd player by analog & digital systems inc. manufactured in january 1986.   and here are some photos...

CAMCORDER DIY LED LIGHT WITH WARM - COLD ILLUMINATION ADJUSTMENT     VIDEO ABOUT THE CONSTRUCTION     very usefull diy led light with warm - cold adjustment perfect for filming videos.it consists of cheap & easy to find components and modules.it is powered of 18650 li-ion batteries and includes charging circuit. the illumination tone can be adjusted to warm - neutral or cold by two potentiometres. it uses a boost converter circuit to keep the output voltage stable for the leds so the light produced remains stable until the batteries are fully discharged. there is also a buck - boost converter for charging purposes that is adjusted to provide a constant current - voltage to charge the batteries.it can be powered from 5-25 volt and the current required is about 2amps. here are the components used...(search with these terms) 3W High Power cool/warm white 3000k 4000k 10000k-30000k LED + 20mm star pcb   AMS1117-ADJ REGULATOR CIRCUIT(build your own)

consider subscribing to this channel and help it grow to produce more quality videos schematics and pcb below

in this video you can see how to replace a dead led from a led array bar of a led tv keep in mind that you should replace all led arrays with new but if the tv set has many led arrays and they are expensive to replace them all then this is the only way. just remember at the end to lower the setting for the backlight from the tv so the leds dont stress to much.

another usefull circuit is the buck converter. A buck converter ( step-down converter ) is a DC-to-DC power converter which steps down voltage (while stepping up current) from its input (supply) to its output (load). here is a pcb that i designed using smd and through hole components for reducing the size of pcb. the only difference is that i used bc869 and not 2n5401 shown in schematics.  the output voltage can be adjusted by the trimm 20k.the pcb i designed uses a multiturn trimpot for higher precision.maximum output current is about 700ma.

with this simple circuit you can turn on-off a relay with 2 tactile buttons.

this is my new youtube channel where you can watch content about electronics,teardowns & repairs and project presentations electronics4all 

the above circuit is a simple but very usefull electronic switch that allows you with a press of a tactile button to switch on or off a load.output current that the circuit can handle depends from the mosfet q2 you use. the circuit is ideal for small projects like a diy led flashlight that you dont want to use a mechanical switch and make it look more professional..i used it to make many flashlights and i designed a small pcb with smd components to fit around the tactile button so you can mount it directly to your project. transistor q1 is not critical and you can use any generic pnp transistor you have laying around. combined with a relay at the output you can make it to switch on-off the output of a bench power supply or an electronic load(i will publish both in the near future).in my tests it can operate from 3.5-25 volts again depending the q2 you are using. pcb and photos coming soon..... q1 can be replaced with:2N3906 - BC557 - BC857 and many more... q2 may be r

this is the first test video i uploaded to my new youtube channel so please forgive the poor quality of the video. in the next videos im making i will provide a more detailed presentation and HD video of this project. if you don't wanna miss it please subscribe . ------------------------------------------------------------------------------------------------------------ this is an adjustable temperature soldering station using arduino uno or pro mini to sense the temperature and control the soldering iron. this circuit-project is used many months now in my workshop.i built 4 of them and gave one as a gift to a friend and all of them work flawlessly. the solder iron used is a cheap hakko clone which uses a type k thermocouple for temperature sensing. notice that i didnt use the L7809 regulator shown in the schematics because it was geting too warm.instead i used a buck converter for the 9 volt output for the lm358 and then a L7805 regulator  to power the arduino.you can a