Solar Minty, DHT22 , Waterproof DS18B20 , PH Probe

This is a work in progress project which uses a Solar charging MintyBoost to power an Arduino with a Proto Screw Shield on it. Attached is a 2X16 LCD using the I2C Backpack, a DHT22 Temperature and Humidity Sensor, a Waterproof DS18B20 Sensor and a 5V analog PH Probe/Adapter.

DC Voltage Doubler - 74HC132

74HC132
This is a cheap DC Voltage Doubler Circuit diagram, which requires a few components and will deliver 10V from a 5V power supply. If the oscillator must be built from a non-functional gate then is required 2 more components: R1 and C3.
The most important parameters of this voltage doubler circuit are given in the table below. Note that because of the IC tolerances these data may have some differences.

SPS250A power supply 2SC2625

A SMPS I take on trips I forgot is NOT auto voltage sensing on input and was still set to 110V after recent US trip.

Pretty obviously the power transistors got fried and rather than junk it I thought I should fix it

This is dealing with mains voltage so do not do this unless you know what you are doing as the voltages are lethal.

It took a bit of digging to find the circuit diagram (thought it was on the pdf that came with it), still haven't found it exactly but this is very similar except mine appears to run the fan full all the time instead of having a fan control board on the lower right here.


These power supplies are widely in use and all are called SPS250A in the name and are all made in China under various names... so if yours has SPS250A in the name and looks like mine then chances are it is the same but no responsibility if it is not, use information at own peril (and this is running at mains voltage which can kill so do not do this without a healthy respect for high voltages).

The two NPN power transistors 2SC2625 were removed still attached to their heatsink.


Note all the common mode filtering on the input side (top right corner).
Mine has had the right hand transistor crater and the other is short circuit between the pins.

Anyway suffice to say power supply can be easily repaired.

I hear that it might make sense to replace the 2Sc2625 10A versions with 2Sc3220 which are 15A versions but I would source them in HQEW.net  .

The digital voltmeter ICL7107CPL

Here is my lovingly-crafted schematic for the voltmeter module. Note that this could be made as a standalone voltmeter, it will measure up to 20v DC. In our finished product, the +5V will be sourced from an LM78L05 voltage regulator.

And the parts list:

    IC1 – Intersil ICL7107CPLZ
    IC2 – Intersil ICL7660
    D1~D3 – 1N4148 diodes
    LED displays – Agilent HDSP521G 2 x 7-segment green displays (common anode). You can use anything really, as long as it is common anode, and each segment is ~8mA
    R1 – 220 ohm – all resistors 0.25W
    R2 – 10k ohm
    R3 – 1M ohm
    R4 – 47k ohm
    R5 – 15k ohm
    R6 – 100k ohm
    R7 – 1k ohm multiturn potentiometer/trimpot (for calibration)
    C1 – 10nF – all capacitors must be rated for at least 25V
    C2 – 20nF
    C3 – 470 nF
    C4 – 100 nF
    C5 – 100 pF
    C6,7 – 10 uF electrolytic

Please note that this is a work in progress and errors may have been made, or values altered at any time after publication.

Best DC power supply 3Amp LM317T

There is the high quality power supply to provide high current 3A. And still adjust voltage in steps from 3V, 6V, 9V, 12V. adjust voltage is continuous 1.25V to 20V. Using LM317T and 2N3055 are main parts so easy to made and cheap.

Friends would known the power supply as well. Because you must use in various circuit experiment. It originally had a small supply current, when found projects that uses lot of current. Such as an audio amplifier circuit so provide current is not enough.
This project can help you. Because of provide high current 3A. And still adjust voltage in steps from 3V, 6V, 9V, 12V. adjust voltage is continuous. And you do not have to worry. This creates a simple and economical. If interested, please read on.

How it works
In the circuit below can be seen that, when opening switch S1 is current through the transformer. To convert from 220V AC to 18V, then through diode bridge rectifier BD1. But is a DC supply that still not smooth. Then, a filter capacitor C1 serves electricity, out of BD1 to be more smooth with the LED1 to show that power is supplied to already.
When the filter current is smooth on one order. The current will through the regulator circuit that the main components are IC1(LM317T) and Q1(2N3055).
-IC1 is the regulator IC number : LM317T.
-Q1 is power transistor NPN type number : 2N3055.

Before the DC volt through IC1 would have C2 served filter noise off. When we adjust the variable resistor VR1 or rotary switches S3 twist choose it. Will cause changes the voltage at the ADJ pin and OUT pin of IC1. Which will be resulting the voltage drop across the base pin and the emitter pin of transistor Q1 changes. Makes the voltage on the connector is changed accordingly. And before the voltage is applied to current C3 filter to smooth again.
Detail see in circuit image.

Make a DIY LM317 Power Supply

     HI. Being able to poke voltages into your projects will help you debug. You can buy an adjustable power supply for $50 or so, or build your own from a kit (another one) Just look for any power supply kit that has a LM317 in it.

    You can also build it for $10 using a 9V battery as input and test clips for outputs. This won’t be able to provide a lot of power (cause its just a 9V) but it can go pretty far for testing and debugging.