Building the Colossus LED Display

by Adam Haile @

The 2014 NC Maker Faire was a huge turning point for Maniacal Labs. It was there that the idea for the AllPixel and what is now BiblioPixel got their start. It’s also where we showed off our first custom-built LED display, the 24×24 LPD8806 matrix. At nearly 24 inches square, and 1 pixel per inch, it was certainly impressive. But we left the Maker Faire with a desire to go bigger. Not just more pixels… but physically larger. Much larger. We call it “Colossus”.

Building the Colossus LED Display – [Link]


Arduino based MPPT solar charge controller

20150805_151734 copy

by Abid Jamal @

what is Mppt( Maximum power point tracking) ?
“we use MPPT algorithm to get the maximum available power from the Photovoltaic module under certain conditions”

How MPPT works ? Why 150W solar panel does not equal to 150 w?
For example you bought a new solar panel from the market which puts out 7 amps. under charge the setting of a battery is configured to 12 volts : 7 amps times 12 volts = 84w (P=V*I) You lost over 66 watts – but you paid for 150 watts. That 66 watts is not going anywhere, but it,s due to the poor match of the solar output current and battery voltage .

Arduino based MPPT solar charge controller – [Link]

Multi Channel Datalogger with OLED Display


by Jed Hodson @

A 3 Channel Datalogger Powered by the LinkIt One. This device can log data from 2 Analog Inputs and 1 Digital Input / Output with PWM capabilities. The Device syncs time from GPS and makes use of the on-board battery to make it become even more portable. With an OLED Display to show system information and live data feed, along with the option to force an update all controlled via the 1 Button. The data file is stored on the LinkIt One’s internal storage and saved as a CSV file so it can easily be read by a text editor or a more powerful program (such as Excel). Fully Customizable and with room to expand all via the software that makes it run.

Multi Channel Datalogger with OLED Display – [Link]

Teardown & Repair of a Stanford Research PS350 5000V, 25W High Voltage Power Supply

In this episode Shahriar repairs a Stanford Research Systems Model PS350 5000V-25W High Voltage Power Supply. The unit continuously displays 2.5kV without the output being enabled and produces no output voltage. Verification of power supply voltages reveals the issue is linked to a disconnected 15V voltage regulator IC. After the repair, the output voltage is verified with both positive and negative outputs. The principle operation of the instrument as well as the Cockroft-Walton high voltage generator is reviewed.

Teardown & Repair of a Stanford Research PS350 5000V, 25W High Voltage Power Supply – [Link]

Raspberry Pi 2 VS Orange Pi 2 VS BPi-M2

In this VS episode “GreatScott” will compare the hardware (CPU, RAM, GPU,….), the software and community aspects of the three most powerful single board computers from the fruit companies.

Raspberry Pi 2 VS Orange Pi 2 VS BPi-M2 – [Link]

Basic Types of Thyristors and Applications

In this article we will discuss about the various types of thyristors. Thyristors are 2 pin to 4 pin semiconductor devices that act like switches. For example a 2 pin thyristor only conducts when the voltage across its pins exceeds the breakdown voltage of the device. For a 3 pin thyristor the current path is controlled by the third pin and when a voltage or current is applied to this pin the thyristor conducts. In contrast to trasistors, thyristors only work on ON and OFF states and there is no partial conduction state between these two states. Basic types of thyristors are: SCR, SCS, Triac, Four-layer diode and Diac.

Silicon Controlled Rectifier (SCR)


Silicon controlled rectifier is normally in OFF state but when a small current enters its gate G it goes to ON state. If the gate current is removed the SCR remains in ON state and to turn it of the anode to cathode current must be removed or the anode must be set to a negative voltage in relation to cathode. The current only flows in one direction from anode to cathode. SCRs are used in switching circuits, phase control circuits, inverting circuits etc.

Silicon Controlled Switch (SCS)


Working of SCS is similar to SCR but also it can be turned off by applying a positive pulse on the anode gate. The SCS can also turned ON by applying a negative pulse on anode gate. The current flows only from anode to cathode. SCS are used in counters, lamp drivers, logic circuits etc.



Triac is similar to SCR but it conducts in both directions, means that it can switch AC and DC currents. The triac remain in ON state only when there is current in gate G and switched OFF when this current is removed. Current is flowing in both directions between MT1 and MT2.

Four layer diode


Four layer diode has 2 pins and works like a voltage-sensitive switch. When the voltage between the two pins exceeds the breakdown voltage it turns ON, otherwise it’s OFF. Current flows from anode to cathode.



Diac is similar to four-layer diode but it can conduct in both directions meaning it can contact both AC and DC currents.

Basic SCR Applications

Basic Latching Circuit


In this circuit a SCR is used to form a basic latching circuit. S1 is a normally open switch and S2 is a normally close switch. When S1 is pushed momentary a small current goes into the gate of SCR and turning it ON, thus powering the load. To turn it off we have to push the S2 push-button so the current through SCR stops. Resistor RG is used to set the gate voltage of SCR.

Power Control Circuit


In this circuit a SCR is used to modify a sinusoidal signal so that the load receives less power than of what would receive if source voltage was applied directly. The sinusoidal signal is applied to the gate of SCR via R1. When the voltage on the gate exceeds the trigger voltage of SCR, it goes to ON state and Vs is applied to the load. During the negative portion of the sine wave the SCR is in OFF state. Increasing R1 has the effect of decreasing the voltage applied to the gate of SCR and thus creating a lag in the conduction time. In this was the load is receiving power for less time and thus the average power to load is lower.

DC motor Speed Controller


This is a variable speed DC motor controller using a UJT, a SCR and few passive components. UJT along with resistors and capacitor form an oscillator that supplies AC voltage to the gate of SCR. When the gate voltage exceeds the triggering voltage of SCR, the SCR turns ON and motor is running. By adjusting the potentiometer the output frequency of oscillator is changing and thus the times the SCR triggered is changing, which in turn changes the speed of the motor. In this way the motor is receiving a series of pulses that average over time and the speed is adjusted.

Basic TRIAC Applications

AC Light Dimmer


This is an AC light dimmer formed by a diac, a triac and some passive components. The capacitor is charging through the two resistors and when the voltage on one end of the diac exceeds the breakdown voltage it goes ON and sends a current to the gate of triac putting the triac to ON state and thus powering the lamp. After the capacitor is discharged to a voltage below the breakdown voltage of diac, the diac, triac and lamp turn off. Then the capacitor is charged again and so on. So the lamp is only powered for a fraction of time during the full sinewave. This happens very quickly and the lamp seems dimmed. Brightness is adjusted using the potentiometer.


Don’t be afraid of heatsinks modifications


If you´d like to use some of standard heatsink profiles, but you need for example an extra opening, we´ll supply it to you customized according to your needs.

Perhaps everyone of us is familiar with a sentence mentioned in various catalogues, á la “upon request we can supply you a customized version”. Naturally that sounds good, but sometimes it is associated with a significantly higher price or with a considerable minimum order quantity (MOQ). That´s why we don´t want to generalize, as every producers behaves differently, but we´d rather like to mention one concrete example – on a heatsink.Aluminium heatsinks certainly belong to a group of components, where a small mechanical modification is very often required. Length, openings, threads, milled ribs,… In fact a small modification, which can make a production of your device significantly easier is available for a quite affordable charge. For example drilling of two openings upon request plus 2x M2,5 threads into some of standard heatsinks costs approx. 0.6-1 Eur, already at 50 pcs order (depending on a producer and a heatsink type).

In case, you don´t have a precise CNC equipment for accurate work with metals ( what´s perhaps the status of majority of small and mid-size companies), a possibility to get such a custom-modified heatsink is usually highly welcome. Maybe it´s worth mentioning, that it´s not about drilling of openings “somewhere” on a heatsink with a questionable position and accuracy, but a quite precise CNC operation.
Small price difference is usually acceptable for every product and you – as a producer – are relieved of further complications with a mechanical modification “in house” or at your local companies.

That´s why, next time you´ll face a question, how to modify a given heatsink, let us know – maybe you´ll be pleasantly surprised.

Don’t be afraid of heatsinks modifications – [Link]

How to Set Up the DHT11 Humidity Sensor on an Arduino



Because of their low cost and small size, DHT11 humidity and temperature sensors are perfect for lots of different DIY electronics projects. Some projects where the DHT11 would be useful include remote weather stations, home environment control systems, and agricultural/garden monitoring systems. The DHT11 is a digital sensor that lets you easily get relative humidity and temperature readings in your projects. In this post, I’ll first go into a little background on what humidity is, then I’ll explain how the DHT11 measures humidity. After that, I’ll show you how to connect the DHT11 to the Arduino and give you some example code so you can use the DHT11 in your own projects.

How to Set Up the DHT11 Humidity Sensor on an Arduino – [Link]

Signal Generation with MATLAB. Example of DTMF in telephony


by  Maurizio @

In mathematics a signal is a real function of a real variable f(t). In electronics it represents the evolution of a voltage (or a current) over the time and depends on the performances of the stage of the amplifier. Through a memory buffer, samples move to a digital-to-analog converter that produces a voltage signal, after an amplification stage that can limit the generation of the signal. A possible analysis consists of use Matlab with a PC sound card and an example of DTMF.

Signal Generation with MATLAB. Example of DTMF in telephony – [Link]