Digital & Binary clock with thermometer & hygrometer

Here we have a clock. It's not "another clock". It has digital and binary 

output. It also has a thermometer and a hygrometer. It's not "another 

thermo-hygrometer". It display's absolutely humidity (gr/m3) also.

Schematic

Click on image to view large

MCU

I build it around Microchip PIC16F917, with internal Oscillator at 4MHz. 

I also build a serial port programmer, so I can programming it on-line, 

using the DL4YHF WinPic.

 Download source code in .asm

Clock

I use a RealTimeClock Maxim DS1305. The RTC backup power is a 

supercapacitor (0,22F). I test  it for 4 weeks, works fine. For this 

reason it don't have the capability to change the time, but you can 

do small-corrections. Once you push the button, the seconds change 

to 30, with no effect to minutes, hours etc. The routine is in lines 

1878-1887 "sec30".

You set the time when you program the PIC. You have to program 

two times. The first time without line 91 (goto  rdtime). The 

routinessetDS and settime is execute.

SetDS is setting RTC's control and trickle charger registers. In the 

settime routine, you set the time. After this, you add line 91 (goto  

rdtime) and you reprogram it. Now the routines do not execute. RTC 

can keep the setting and time at least for 28 days. The routinesDST3 

and DST10 are for DaySavingTime. The check register is flag, 1. The 

checking routine is in lines 434-460. In the last Sunday of March, the 

02:00 o'clock became 03:00 o'clock. In the last Sunday of October, the 

02:00 o'clock became 01:00 o'clock. I set the RTC for 12H mode, leds 

for 12H and display for 24H.

Temperature - Humidity

I use a digital humidity and temperature sensor Sensirion SHT11.
I bought it in a PCB, with the pull-up resistor and decoupled capacitor 

ready in place.
Measurements make every 10 seconds.
At 00, 20 and 40 seconds it measures the temperature and calculate 

the temperature and Absolutely Humidity ("gr/m3" grams at cubic meter of air).
At 10, 30 and 50 second it measures the humidity and calculate the 

Relative Humidity (%).
The check register is flag, 0. The checking routine is in lines 464-475.
The measure temperature routine is in lines 477-514 "measTEMP" 

and lines 625-714 "measure".
The calculate temperature routine is in lines 1793-1820 "calcTEMP".
The measure Relative humidity routine is in lines 560-590 "measRH" 

and lines 625-714 "measure".
The measure Absolute humidity routine is in lines 515-555 "measAH".
The calculate Relative humidity routine is in lines 717-1470 "calcRH".
The calculate Absolute humidity routine is in lines 1473-1728 "calcAH".

LCD display

I use a Chinese display 2line, 24row, with backlight. I drive it with a 

sift register T.I. 74164.

LED display

I use bright leds. 7 green with 8,2K resistors for seconds, 7 white with 

5,6K resistors for minutes and 5 blue with 560R resistors for hours.The 

maximum current for leds is about 17mA, so I don't have to drive them 

with transistors.

PCB

The PCB build in DipTrace software.  Download DipTrace files here
BEFORE PRINT:
1.      In print preview click on "Objects" tab. UNCKECK Assy and Silk
2.      CHECK Mirror
3.      CHECK Print in black only
4.      BE SURE print scale 100%.

Super Flux RGB LED Controller

ntroduction

 
In this project it was used the “Piranha Super-flux RGB” Led of common 

anode, and the PIC18F25K20, in order to generate combinations of colors. 

It has two function modes, automatic that generate the color sequence 

that is stored in the μC memory, and the manual mode in which you can 

select one of the seven possible colors.

Schematic

Firmware

 
The control of the RGB led is made with PWM(Pulse With Modulation), 

because PIC18F25K20 only have 2 PWM outputs (Hardware), I did the 

PWM by software to have 3 PWM outputs for that I use TIMER0 and for 

the Manual mode I use IOC(interrupt on change).

 

De-bounce

In this project I use push buttons to change between modes and to 

change the colors. But if we use the button as in the circuit (1) we 

have a problem. The problem with this configuration, due to the 

mechanical nature of any switch that may contains spring return 

action of some kind, there won’t be a clean transition from a state 

to another, but instead there will be a series of high and low states 

spikes. To solve that problem we have to implement a de-bouncing 

system, it can be done by hardware or software. We can use a RC 

delay circuit or it can be done with a schmitt trigger, but both ways 

will increase the price. So I done by software the de-bounce.

Example of code to do de-bounce:

It can be done in a different away but this way works for me.

PSU

I use a 7812 voltage regulator to keep the voltage stable in the RGB led and for 

μC I use an LM317 voltage Regulator. To calculate the output of LM317 I use this equation:

Led RGB

I use different resistor values on the RGB Led because which color have a different 

VF (Forward Voltage) in order to have the same LUX for each color. To calculate 

the resister I use these equations:

Download

 Download Bill of material in PDF format
 Download schematic in PDF format
 Download firmware in .hex
 Download demo video

A Very Simple Power Failure Light

Introduction

This is a very basic power failure lighting circuit based around a relay.

This simple circuit has many uses, from lighting up rooms and walkways in the case of 

a power failure, to monitoring and security uses.

There are many different power failure circuits out there based on 555 

timers or transistors but they all have different problems including limited 

input voltage, price and complexity, and poor backup power. This unit has 

been designed to work with mains power all the way down to 5 volts, and 

power 3 LEDs to provide light for a hallway or a child's room in the event 

of power failure. The PCB includes many simple add-ons and modifications 

too. 

Specs 

Input Voltage Max: 240 Volts AC

Input Voltage Min: 5 Volts DC

Approximant Power Consumption: 450 mW

Schematic

Explanation

This circuit is connected to ac power through J1 then rectified to dc through 

D1-D4. D5 is a 12 volt zener diode being used along with the resistor R1 

and the coil resistance of relay RL1 to regulate the input voltage to 12 volts 

and C1 is used to help smooth this power.

Alternatively a dc voltage of 5 volts or more can be connected directly to J2 

and J3, positive to J2 and negative to J3; in this setup the circuit would not 

need J1, D1-D5, and R1.

The relay RL1 is a SPDT 5vDc relay and when power is applied to it, it opens 

the circuit with the LEDs so they are off as long as power is on if the power 

goes off, the relay closes the circuit and the battery BAT1 powers the LEDs 

D6, D7, and D8. In this circuit BAT1 is a 9 volt battery that powers the 

3 LEDs through R3; however BAT1 can be many different batteries depending 

on your needs. J4 is also available in parallel with the LEDs to connect a

buzzer or etc.

You can also put a switch on one of the wires for BAT1 so you can turn it 

off so that you 

don't drain it when the circuit is not being used.

Parts List

1	R1	1.2k Ohm
1	R3	120 Ohm
1	C1	470uF
4	D1-D4	1N4004
1	D5	1N4742A
3	D6-D8	White LED
1	RL1*	5 Volt SPDT Relay T7CV5D-05
1	BAT1	9V
1	-	9V Battery Connector

*There are many different relays that can be used, some that even use 

next to no power.

PCB

Download

 Download this project in .DOC format

Motorized Curtain with Remote control

Introduction

The project is "Motorized Curtain" with Remote control. It is made 

up of MCU ATMEGA328 with Arduino BootLoader, motor driver L293D 

( i used L293B with external diodes, because i couldn't find L293D ), 

IR Receiver TSOP 1738, DC Motor from an old printer and other 

small parts. To control it, i use IR remote control from a PixelView 

TV Tuner. The software allows moving the curtain from left to right 

and back, or on steps. On the last peg (of the curtain rail) is 

attached a small magnet, which interacts with the two reed 

contacts, placed on the two ends of the rail. The last peg is 

moved by a cord, which connects it to the motor on one side 

and a reel to the other.

Source Code is written on Arduino. I use NECIRRcv Libraries for decode 

code from IR Remote Control.

Schematic

Photos

Download

 Download source code

Digital Impulse Relay

Introduction

In the first place, a relay is like a switch to a coil assembly. 

This switch is activated when electricity is applied to the coil. 

With a common relay, the electricity must be continuously 

applied to the coil to maintain the contacts, but the impulse 

relay "remembers" and only requires a momentary application 

of electricity. Stated differently, apply pulse of electricity to 

the coil to turn on the relay contacts, apply another pulse of

 electricity to turn off the relay contacts.      

So, impulse relay use it for to turn on a lamp with pushbuttons 

and not toggle switches. What is really neat is connecting 

several momentary pushbuttons in parallel and placing them 

in different locations. I can turn on the lamp in one room, and 

turn it off from a different room, because it was the relay that 

was providing electricity to the lamp, not the switch.

Description

A digital impulse relay is a electronic circuit that mimics perfect 

the all functions of a impulse relay with ratchet mechanism: the 

first press to the button turns the relay on and the second press 

turns it off, and relay in the circuit operating room illuminates. 

Particularity of this circuit is that it can be used in a centralized 

system for home automation. Another advantage is lower price 

compared with that of the impulse relay with ratchet mechanism. 

Digital impulse relay is immune to electrical noise, connection 

between buttons and circuit can be achieved with unshielded cable 

and any length.

Schematic

This circuit is operating the room illuminates. The basic component 

of the circuit is a IC1 (CD4017). Push buttons room are connected by 

normally wired to the circuit. All circuit is separately by optocoupler, 

which means that the circuit is immune to electrical noise that can 

come on cable that connects with push buttons.

First any button push put to GND the optocoupler IN. The output 

signal from optocoupler is amplified by transistor Q1 (BC557) 

together by C1, R3, R4 circuit.  The amplified signal is attack to 

clock pin 14 of decade counter IC1 (CD4017), the counter advances 

by 1, pin 2 goes high and relay is ON. Transistor Q2 (2N2222) 

connected to pin 2 of IC1 drives 12V relay. Diode 1N4004 (D1) 

acts as a freewheeling diode. LED1 indicate the ON/OFF status.

Second any button press, the IC1 advances by 1, pin 2 goes low, 

relay is OFF, and pin 4 goes high. If we connect by diode D2, pin 

4 to Reset pin of CD4017, the counter is going back to the initial

 condition, and is ready to get another button press, to turn the 

relay ON.

The C2 - R6 component keep the Reset pin to +12V, when the 

circuit is powering, until the C2 loaded at 12V.

From transistor Q2 colector is IN/OUT for use in to microcontroller 

system (GSM remote control, WEB control, etc.). When use as IN, 

microcontroller system can put to GND Q2 colector, and relay is ON. 

Or the colector is use as OUT, signal obtained say the microcontroller 

system, if the relay is ON or OFF.

The power supply for the circuit is DC 12V. In standby, when relay is 

OFF, digital impulse relay consume 0V. Otherwise, when relay is ON, 

consume depend of 12V relay current.

Installation

 

Parts List

 

IC1 - CD4017
Q1 - BC557
Q2 - 2N2222
OK1 - PC817 (optocoupler)
D1 - 1N4004
D2 - 1N4148
R1 - 3 K
R2 - 100 K
R3 - 1 K
R4 - 10 K
R5 - 1 K
R6 - 100 K
R7 - 1 K
C1 - 100 nF
C2 - 100 nF
С3 - 1 uF/25V
С4 - 1 uF/25V
С5 - 1 uF/25V
С6 - 1 uF/25V
LED1 - led diode
K1 - 12V relay

PCB

 Download PCB and Schematic Eagle files

Photos

Download

 Download this project in DOC format
 Download PCB and Schematic Eagle files