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Posts posted by sam.moshiri

  1. As we all know, the COVID-19 outbreak hit the world and changed our lifestyle. In this condition, Alcohol and hand sanitizers are vital fluids, however, they must be used properly. Touching alcohol containers or hand sanitizers with infected hands can spread the virus to the next person. In this article, we will build an automatic hand sanitizer dispenser that uses IR sensors to detect the presence of a hand and activates a pump to pour the liquid on the hand. The intention was to find the cheapest and easiest solution and design a circuit. Therefore no Microcontroller or Arduino has been used. Two designs have been introduced and you are free to select and build any of them. The first design uses SMD components and the second design is even simpler. It uses DIP components on a small single layer PCB board.





    Article: https://www.pcbway.com/blog/technology/DIY_Automatic_Hand_Sanitizer_Dispenser__without_Arduino_or_MCU.html

    [1]: AMS1117-5.0 Datasheet: http://www.advanced-monolithic.com/pdf/ds1117.pdf

    [2]: LM555 Datasheet: http://www.ti.com/lit/ds/symlink/lm555.pdf?&ts=1589508422474

    [3]: TSOP1738 Datasheet: https://eu.mouser.com/datasheet/2/427/introductionpartnumbers-1766653.pdf

    [4]: NDS356 Datasheet: https://eu.mouser.com/datasheet/2/308/NDS356AP-D-1813031.pdf

    [5]: AMS1117-5.0 Schematic Symbol and PCB Footprint: https://componentsearchengine.com/part.php?partID=2376678

    [6]: LM555 Schematic Symbol and PCB Footprint: https://componentsearchengine.com/part.php?partID=380204

    [7]: TSOP1738 Schematic Symbol and PCB Footprint: https://componentsearchengine.com/part.php?partID=1116997

    [8]: NDS356 Schematic Symbol and PCB Footprint: https://componentsearchengine.com/part.php?partID=840198

    [9]: CAD Plugins: https://www.samacsys.com/library-loader-help

    [10]: LM393 Datasheet: http://www.ti.com/lit/ds/symlink/lm393-n.pdf?&ts=1589509317025

    [11]: BD140 Datasheet: https://www.mouser.com/datasheet/2/149/BD140-888626.pdf

    [12]: LM393 Schematic Symbol and PCB Footprint: https://componentsearchengine.com/part.php?partID=298790

    [13]: BD140 Schematic Symbol and PCB Footprint: https://componentsearchengine.com/part.php?partID=166782

  2. LM317 is one of the most popular adjustable regulator chips. The output voltage of the regulator can be adjusted from 1.25V to 35V. However, the chip can deliver currents up to 1.5A which is not enough for some power applications. In this article/video, I will discuss two methods of LM317 current boosting, using power PNP and NPN pass transistors.





    Article: https://www.pcbway.com/blog/technology/LM317_Current_Boosting_Secrets.html

    [1]: LM317 Datasheet: http://www.ti.com/lit/ds/slvs044x/slvs044x.pdf

    [2]: LM317 Library: https://componentsearchengine.com/part.php?partID=299235

    [3]: MJ2955 Datashet: https://www.mouser.com/datasheet/2/308/2n3055-d-1190033.pdf

    [4]: MJ2955 Library: https://componentsearchengine.com/part.php?partID=697997

    [5]: 2N3055 Datahseet: https://www.onsemi.com/pub/Collateral/2N3055-D.PDF 

    [6]: 2N3055 Library: https://componentsearchengine.com/part.php?partID=788620

    [7]: CAD Plugins: https://www.samacsys.com/library-loader-help




    • AC – DC Conversion
    • Double output voltages (Positive – Ground – Negative)
    • Adjustable positive and negative rails
    • Just a Single-Output AC transformer
    • Output noise (20MHz-BWL, no load): Around 1.12mVpp 
    • Low noise and stable outputs (ideal to power Opamps)
    • Output Voltage: +/-1.25V to +/-25V 
    • Maximum output current: 300mA to 500mA 
    • Cheap and easy to solder (all component packages are DIP)


    A double output low noise power supply is an essential tool for any electronics enthusiast. There are many circumstances that a double-output power supply is necessary such as designing pre-amplifiers and powering OPAMPs. In this article, we are going to build a linear power supply that a user can adjust its positive and negative rails independently. Moreover, just an ordinary single-output AC transformer is used at the input.



    Source: https://www.pcbway.com/blog/technology/Low_Noise_Adjustable_Linear_AC_DC_Power_Supply.html

    [1] LM317 Datasheet: http://www.ti.com/lit/ds/slvs044x/slvs044x.pdf

    [2] LM337 Datasheet: http://www.ti.com/lit/ds/symlink/lm137.pdf

    [3]: Schematic Symbol and PCB Footprint for LM317: https://componentsearchengine.com/part.php?partID=248007

    [4]: Schematic Symbol and PCB Footprint for LM337: https://componentsearchengine.com/part.php?partID=290650

    [5]: Altium Plugin: https://www.samacsys.com/altium-designer-library-instructions

  4. The STM8S001J3 is an 8-bit microcontroller that offers 8 Kbytes of Flash program memory, plus an integrated true data EEPROM. It is referred to as a low-density device in the STM8S microcontroller family. This MCU offered in a small SO8N package. In this article, we are going to build a programmable Police LED Flasher device that can be used for vehicles, motorcycles, and bicycles.


    Schematic + PCB + Code + Full Description



    Source: https://www.pcbway.com/blog/technology/Programmable_Police_LED_Flasher_Using_an_STM8.html

    [1]: https://www.st.com/resource/en/datasheet/l78m.pdf

    [2]: http://www.ti.com/lit/ds/symlink/lm1117.pdf

    [3]: https://www.st.com/resource/en/datasheet/stm8s001j3.pdf

    [4]: http://www.vishay.com/docs/91192/sihfl110.pdf

    [5]: https://componentsearchengine.com/part.php?partID=1049204

    [6]: https://componentsearchengine.com/part.php?partID=4735

    [7]: https://componentsearchengine.com/part.php?partID=4735

    [8]: https://componentsearchengine.com/part.php?partID=179508

    [9]: https://componentsearchengine.com/part.php?partID=235673

    [10]: https://www.samacsys.com/altium-designer-library-instructions

  5. A tiny DC to DC buck converter board is useful for many applications, especially if it could deliver currents up to 3A (2A continuously without heatsink). In this article, we will learn to build a small, efficient, and cheap buck converter circuit.



    Full Article: https://www.pcbway.com/blog/technology/DC_to_DC_Buck_Converter_Adjustable__97__Efficient__3A.html

    MP2315 Library: https://componentsearchengine.com/part.php?partID=930350

    Altium Plugin: https://www.samacsys.com/altium-designer-library-instructions


  6. nmmgr3a.jpg


    YouTube: https://youtu.be/AJvhhS8I3Ps



    Identify a fake Lithium-Ion/Lithium-Polymer/NiCd/NiMH battery

    Adjustable constant current load (can also be modified by the user)

    Capable of measuring the capacity of almost any kind of battery (below 5V)

    Easy to solder, build, and use, even for beginners (all components are Dip)

    An LCD user interface



    Board Supply: 7V to 9V(Max)

    Battery Input: 0-5V(max) – no reverse polarity

    Constant Current Load: 37mA to 540mA(max) – 16 Steps – can be modified by the user


    The true measurement of a battery’s capacity is essential for many scenarios. A capacity measurement device can solve the problem of spotting fake batteries as well. Nowadays fake Lithium and NiMH batteries are everywhere which don’t handle their advertised capacities. Sometimes it is difficult to distinguish between a real and a fake battery. This problem exists in the spare batteries market, such as cell phone batteries. Furthermore, in many scenarios, it is essential to determine the capacity of a second-hand battery (for instance a laptop battery). In this article, we will learn to build a battery capacity measurement circuit using the famous Arduino-Nano board. I’ve designed the PCB board for dip components. So even beginners can solder and use the device.



    Article source: https://www.pcbway.com/blog/technology/Battery_capacity_measurement_using_Arduino.html

    [1]: https://www.onsemi.com/pub/Collateral/LM358-D.PDF

    [2]: https://componentsearchengine.com/part.php?partID=671517

    [3]: https://componentsearchengine.com/part.php?partID=617283

    [4]: https://componentsearchengine.com/part.php?partID=368895

    [5]: https://www.samacsys.com/altium-designer-library-instructions



    Differential signal measurement in practice

    To measure a differential signal, we have two options, one is using a differential probe and second is using a two channels oscilloscope. A differential probe is expensive but handles a better accuracy. Using two/four channels oscilloscope is the cheapest method which handles acceptable results.

    Just you need to connect oscilloscope’s Channel-1 to one of the differential lines/wires and Channel-2 to another one. Then go to the math function and enable CH1-CH2 which means a difference. Then adjust the oscilloscope to observe the signal. You use the run/stop or a single shot button to freeze the signal on the screen and examine it.

    I have examined the ADSL2+ signal on the telephone line using the above-mentioned differential measurement method.


    Reference: http://bit.ly/2Z7sDTt

  8. Switching power supplies are known for high efficiency. An adjustable voltage/current supply is an interesting tool, which can be used in many applications such as a Lithium-ion/Lead-acid/NiCD-NiMH battery charger or a standalone power supply. In this article, we will learn to build a variable step-down buck converter using the popular LM2576-Adj chip.





    Cheap and easy to build and use

    Constant current and constant voltage adjustment [CC, CV] capability

    1.2V to 25V and 25mA to 3A controlling range

    Easy to adjust the parameters (optimum use of variable resistors to control the voltage and current) 

    The design follows the EMC rules

    It is easy to mount a heatsink on the LM2576

    It uses a real shunt resistor (not a PCB track) to sense the current

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