Best posts made by ceech

The board charges super capacitors and balances them when the system voltage is available. If this power rail fails, super capacitors power bank takes over and sends power back to the power rail - it acts as uninterruptible power supply.

Two capacitors are connected in series, pairs in parallel.
System voltage can be from 3.3V up to 5V. Charging current is 600mA. Backup voltage is 3.15V. The main IC is LTC3110 and it handles all functions of the board.

This board is intended to be a test board for super capacitor chargers and can supply backup power for limited amounts of time.
10 boards will shortly be available for sale and design files will be available at OpenHardware.

Would you like to make some 3D pictures of your PCB? Like this one:

Or some closeups like those:

You can do it with a tool that's called EagleUP. EagleUP exports the data from EagleCAD to Google Sketchup. There you can view, modify and export 3D models.
To run eagleUp you need to download and install:

Cadsoft Eagle
Sketchup
ImageMagick and
EagleUP

Here is a nice tutorial:
https://eagleup.wordpress.com/installation-and-setup/

Enjoy.

The board will receive a new design with TP4056 battery charger.

Charge current and battery voltage will be reported on ADC6 and ADC7.
Mosfet will be available for external load regulation. It is connected to D3.
There are three sockets for:
bluetooth
NRF24l01+ and
I2C modules.

Here are two new boards. Their purpose is to replace batteries in wireless sensor nodes in places where batteries are not appropriate, available or recommended for use.

The first one is a Thermal Energy Harvester which uses thermopile or thermoelectric generator as a power source:

This board uses a transformer to step-up the voltage and works with voltages as low as 20mV. Here is an intended use:

There are three outputs:
Vout
Vout2 and
VLDO
Vout and VLDO turn on as soon as the voltage on those pins is within regulation and Vout2 turns on when the Vout2_EN signal receives a high on its pin from a microcontroller, for example.

And the second one is a Solar Energy Harvester which is powered by a small 5 - 20V solar cell:

The IC can operate with up to 60V of input voltage and has a built-in CC and CV algorithm.
There are also some settings available for this one:

User can choose output voltage and charge current and also MPPT point of solar cell.
This power supply can act as a battery charger as well.

Both boards are designed to fit on top of sensor board:

to help with connections

Finally managed to put all things together and made the first two test boards. They look like this:

Main new features are LTC4067 lithium battery charger and XC6210, a low consumption voltage regulator.

The board comes with a Torex XC6210 3.3V voltage regulator . It has low power consumption of 35μA, while delivering at least 700mA. Voltage drop is 50mV @ 100mA.

LTC4067 battery charger with Automatic Battery Charging/Load Switchover

It provides power for the circuit and charges the backup single-cell lithium battery while greatly extends battery life. You can monitor the voltages and currents. It has suspend mode, which reduces current consumption to around 40μA. The power source is a small, 5V solar cell. Connections:

analog input A1 on ATmega 328 is FAULT signal from LTC4067
analog input A0 on ATmega328 is battery voltage
analog input A2 is solar cell voltage
analog input A6 is input current ( I=V/R x 1000 )
analog input A7 is battery charge current ( I=V/R x 1000 )
digital output A9 - drive it high to put LTC4067 in SUSPEND mode

The two trimmer potentiometers are used to determine the current for both the input side - to better match the internal resistance of the solar cell - and for the battery charge current. At shipping they are both set to about 2.5kOhm, which set both currents to about 75mA. Please refer to technical data sheet of LTC4067 for more information. It is available here:
Official web page for LTC4067

Or, ask me.

This is the back side of the board with place for BMP180, HTU21 and EEPROM chip:

There is something similar I'm working on. Although mine is more like a solid state relay. And it can be used as an AC dimmer. But has the same concept with AC-DC converter. I used one from Vigortronix. It has a 3.3V output.

Here it is controlled with Bluetooth serial connection

This is how the board looks like

If anyone wants it, let me know.

@aproxx I like your form factor. Great find with that AC-DC converter.

The charger can be something like this one:
http://www.ebay.com/itm/LM2596-DC-DC-Step-down-Adjustable-CC-CV-Power-Supply-Module-Converter-LED-driver-/191673918658?hash=item2ca0a7e4c2:g:4H4AAOSwMmBVo4rQ

It has a buck converter with constant current and constant voltage settings which is what batteries need. It can charge any kind of battery with proper float voltage and current settings. If you would go with 4 lithium cells in series you can use the same module to charge the batteries and use it to drive LEDs. Multiple cell lithium batteries normally also need a balancing circuit. Not absolutely necessary, although recommended.

Here is a link to a video on driving LEDs with this converter:
High Power LED Tutorial #1 - How to Drive 1W and 3W LEDs from 12 Volts – 07:56
— Julian Ilett

Anyone interested in super capacitors.
I'm working on a backup super capacitor storage board. It connects directly to the power rail and charges and balances super capacitors bank. When and if power fails the board steps in and provides power to the circuit.

It is based on LTC3110 super capacitor bi-directional charging IC.

@mfalkvidd Removing --my-controller-ip-address did in fact solve the issue.
Thank you for your help.
So, to sum up, these are commands to be used when configuring Gateway for Domoticz ethernet (LAN) connection:

./configure --my-transport=nrf24 --my-gateway=ethernet

make
sudo make install

sudo systemctl enable mysgw.service # << adding to boot
sudo systemctl start mysgw.service # << starting

There is a project I've been working on that I would like to share. It is not a sensor board for home automation, it is more like a development board. There are some sensors on it which can be used, though. It has BMP180 temperature sensor, a LSM9DS1 3D accelerometer, gyroscope & magnetometer and real time clock. This is how it looks like:

The idea is to use those sensors and display its values on the front of the board. Time for example. Microcontroller is an ATmega 2560 with mega bootloader and is Arduino compatible. It can be powered with a rechargeable coin battery or via USB. I'm working on a prototype at the moment and it will soon be ready.
I made it because I would like to show that Europeans are as much proud of their heritage as Americans and lately Britons.
Is there someone who would like to help write some code for it? And what do you think about it?

@AWI
I normally use a 12V car battery, for monitoring different values in the car. When the board is used in single cell battery applications, I go with a different type of voltage regulator. Normally I use TC2117 3.3V voltage regulator. Unfortunately those regulators are not available for purchase either form Farnell nor Microchip at the moment. They will be available on the 9th of March. So a bit of a set back. As for the enclosure, I use this:

And a little 5V solar cell, when appropriate:

there is also a matter of battery charging, which I leave to this fellow:

http://www.ebay.com/itm/221533778016?_trksid=p2060778.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I'm also preparing a new board, with integrated battery charger for LiPo, LiIon batteries and some other cool features.

@AWI Here is a graphical explanation of the socket connections:

SDA and SCL lines also have pull-up resistors. They are 10k.

@lafleur The board is meant to be used with either NRF24l01+, or ESP8266 radio modules. @hawk_2050 The price will be around 14EUR for the version without sensors, and 19EUR for the fully populated one. @Sparkman and @sj44k some boards will be available as soon as next week. Those are the test ones and since everything seem to work excellent, I'll make them available for purchase.

@Fabien @DrJeff Here is a link to board and schematic files for the transformerless AC-DC converter:
https://github.com/ceech/AC_SR087

@doesel33 Your board came back. No one claimed the package at your post office and after two weeks it came back. Take a look, I still have the envelope:

So, what do you want to do with it?
Maybe there is an error in your PaPay entered address or something similar. Would you check that? I'll be happy to send you a package again.

New boards are ready and are being tested. Here is one connected to a Bluetooth module charging a battery:

This is the code used in battery voltage and charge current monitoring:

float readVcc() 
{
  signed long resultVcc;
  float resultVccFloat;
  // Read 1.1V reference against AVcc
  ADMUX = _BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
  delay(10);                           // Wait for Vref to settle
  ADCSRA |= _BV(ADSC);                 // Convert
  while (bit_is_set(ADCSRA,ADSC));
  resultVcc = ADCL;
  resultVcc |= ADCH<<8;
  resultVcc = 1126400L / resultVcc;    // Back-calculate AVcc in mV
  resultVccFloat = (float) resultVcc / 1000.0; // Convert to Float

  return resultVccFloat;
}

const int current = A6;
const int lipo = A7;


float vout = 0.0;
float vin = 0.0;
int value = 0;

void setup() 
{
  Serial.begin(9600);
}

void loop() 
{
  float napetost = readVcc();

  float tok = ((analogRead(current) * napetost / 1024 ) * 1200) / 3; // convert the ADC value of charge current to miliamps
  float baterija = ( analogRead(lipo) * napetost / 1024 ) * 2; // measuring battery voltage
  
  Serial.print("Vcc = ");
  Serial.print(napetost);
  Serial.println("V");
  delay(400);
  Serial.print("Charge current = ");
  Serial.print(tok);
  Serial.println("mA");
  delay(400);
  Serial.print("Battery voltage = ");
  Serial.print(baterija);
  Serial.println("V");
  delay(400);
  Serial.println("----------------------------");
  delay(2000);
}
/*
Improving accuracy:
To do so, simply measure your Vcc with a voltmeter and with our readVcc() function. Then, replace the constant 1107035L with a new constant:
scale_constant = internal1.1Ref * 1024 * 1000
where
internal1.1Ref = 1,1 * Vcc1 (per voltmeter) / Vcc2 (per readVcc() function)
Example:
For instance, I measure 3,43V from my FTDI, the calculated value of Vref is 1,081V.
So (1,081 x 1000 x 1024) = 1107034,95 or 1107035L rounded up.

Use smoothing example from IDE to smooth the data from ADC.
*/

Charge current is limited to 400mA and can be easily changed to another value by changing just one resistor.

@alexsh1 @NeverDie You can substitute the MAX8887 with MIC5365.
This whole thing got me so intrigued that I'm going to make a board myself. With charger, super capacitors and DC-DC converter. I'll use MIC5365 and for DC-DC conversion TPS610986. It has loads of options. And the whole thing will cost less than 10 bucks. I've made a schematic

Added. MIC5365/6's package is SC-70-5.

@epierre It's finished as well and tested working.

Next will be the particle one.

@mfalkvidd First thing one does is to follow instructions exactly and hope things will work out. They don't. You try a different type of connection. Which one? Why one or the other? Which option among the same type? It doesn't work, either. Now, you are thinking, ok this guide is for several controllers, so how do I adapt it for my specific case.
The point being, you can't adapt the instructions on your own. You have to ask someone who's done it before and knows what commands to use in order to make Gateway connect to the specific controller.
For example: using
--my-gateway=ethernet --my-controller-url-address=YOUR-CONTROLLER-ADDRESS
will never connect your Gateway to Domoticz. How can one know that this is the line to be modified?

This is quick tip on how to drive a power mosfet transistor with a small one. Let's say that we would like to drive a pump with a wireless signal and that we have one of those boards with a N channel mosfets on:

We need to make a few modifications:

Connect D3 and D4 with a bridge, change a D1 diode with a 1k resistor and connect:

Those changes make up to this schematics:

And here are the signals:

The blue signal is the output from the digital pin D3( PWM ), and the yellow signal is the signal on the gate of the power mosfet, which is a P channel mosfet.

@NeverDie One of the problems is the charge/discharge curve:

As you can see the capacitor loses a lot of its charge in the moments right after it starts discharging. It holds the bottom half of the charge better. They are useful for short pulses of energy. But they are not batteries by any means.

Source: http://www3.ncc.edu/faculty/ens/schoenf/ELT115/UCC.html

And the other is an improper measurement. The multimeter draws current from capacitor. Anyway here is a graph of self discharge rates by capacitor type:

Source: http://www.robotroom.com/Capacitor-Self-Discharge-1.html

This board is made for low-power applications and can be used as an universal board for wireless sensor node networks. It can be powered from battery or external source. Dimensions are 2 inch x 2.1 inch.

There are three sockets:

• for NRF24l01+ module
• for ESP8266 ESP-01
• and an I2C socket

The board is powered with a Microchip MCP1703 3.3V voltage regulator.

On the back, there is place for BMP180, HTU21, additional EEPROM and for TC series Mosfet driver.

Here is a link to the schematic: http://i.imgur.com/DbALMmf.png

The board is available here, on http://www.mysensors.org/hardware/ceech

@Dany Yes, it can. While those boards are mostly used for short energy bursts, I made some continuous current draw measurements. I've attached an LED with current draw of 3.5mA. The board provided 20 minutes of power while dropping the voltage from 2.3V to 1.86V.

@scalz Here you go:
https://github.com/ceech/AC-dimmer
Enjoy.

@epierre You can use a Peltier element to power this board. Like this one:

http://www.ebay.com/itm/TEC1-12706-12V-60W-Heatsink-Thermoelectric-Cooler-Cooling-Peltier-Plate-Module-/121349774916?hash=item1c41029e44:g:mukAAOSwDNdVrg-U

@MikeF Here you go:

schematic

and board

Ah, yes. I think i know what the problem is. The LTC4079 has a built-in MPPT power tracking for solar panels and won't charge if the input voltage is below set point. This helps optimizing power extraction from solar panels. If you are using 5V input, then you should adjust the trimmer pot on the board. Like this

Turn the top round part of the trimmer to the left so that the wiper reaches 5V mark like on the above picture. In other words reduce trimmer resistance to minimum. The other way around is for 18V solar panels.

@alexsh1 Boards will be most likely available by the end of the week.

The float, or better cut-off voltage for NiCd batteries is between 1.5V and 1.6V per cell.
Programming resistor of 3k equals to 100mA of charging current and 1180 ohm equals to 250mA, which is a maximum value that the LTC4079 can handle (it gets too hot at this value). I equip the boards with 3k resistors.
Batteries can be charged with different currents. One option is 0.1C (the C rate is the hour capacity of the battery). That is 10% of battery's nominal value. For 1000mAh battery that would mean 100mA.
I pulled timer to ground which means that the charger will stop charging at C/10 or 10% of programmed current, or 10mA in case where a 3k resistor is used. This works fine for lithium batteries.
NiCd or NiMH batteries should be charged with timer limit as you mention. It is not absolutelly necessary in our case. Let me explain. If you charge a NiCd battery with a 0.1C, that means that the battery will be fully charged in approximately 14 hours. So the sunset will be the timer that we need. And even if we charge the battery all the time a C/10 termination will reduce the charging current to a value which is close to a battery's self-discharge rate, thus keeping the battery voltage on safe levels.
There is also battery voltage monitoring circuit on the board which can be used to report whenever the battery voltage is out of bounds.

@NeverDie 20mV is stat-up voltage.

Here it is

There are still some bugs to eliminate

but it works

And I'm quite happy with the result.
Does anyone have any experience driving ATmega2560 at 3V? I'm considering removing boost converter circuit and power the flag with just a coin cell battery.

@NeverDie I like those:
http://www.mouser.com/ds/2/40/AVX-SCC-1018831.pdf
Super capacitors will be installed on boards.

A few boards arrived and a couple are assembled

The board charges four 1.5F 2.7V super capacitors. It also provides a boost circuit with 3.45V output on main and sub outputs. It works down to 180mV and provides 3.5mA for 30 minutes. I'll report on leakage.

There are two outputs main and sub. Main is on all the time and sub is switched with high signal on the mode connector.

Noise isn't bad at all. Surprisingly. It is no bigger than the background noise when no input is connected.