EEPROMshield

The PCB design of my EEPROM test/development shield is ready. 
Hope to post soon (after receiving the PCB), more details and test results of this Arduino shield on this blog.
This PCB is a breadboard friendly Arduino shield for multiple EEPROMs.  September 2020 the final design (using EasyEDA ) for the first version this board was ready. However i decided to wait for ordering  this PCB until i tested an EEPROMs. 

Mailbag 29 augustus 2020

Below new mailbag items.
As they are often needed for small projects some switches. On the photo you can see the foam package for protection during the transport.

 

As for less than 5 euro's it is possible to buy a small weighing scale on AliExpress For long time i had this on my wish list and some weeks ago I decided to buy one (300g/0.01g.). Not only can it become quite handy for counting electronic parts, I also hope to find time for chemistry or physics experiments. I expect it is more easy to use than the old analytical balance i have. When i started doing chemistry experiments many years ago i did never dream i could buy this instruments below 5 euros. I hope to do a full review including testing with some weights. What i already can say, it is small and looks nice. The front already had some scratches (see photo) and i had some trouble opening the back for placing the two AAA batteries. The 0.01 gram display looks stable during weighing 

 

Below some gloves to protect my hands. I was very happy with some other gloves i used before. However after some time working in the garden holes started to appear and I could not find the same one so i decided to try this gloves from China / Aliexpress.   

EPROM eraser (UV)

Received an UV EPROM eraser from china so i can wipe the content some old classic memory chips that i still have so i can use them in future projects.  On the top right is the on/off switch. The 'rotating knob' on the top left is a mechanical timer to set the UV exposure time.

Here a picture where you can see the bottom. I don't know what is the original idea of the hole in the little drawer. When i switch the device on i can see some of the light inside this compartment where the EPROMS need to be placed.

The device came sooner than expected. I expected an EU power plug, however that is easy to fix. The 220Volt seems, according to the description no problem.
I don't have the electronic circuit ready to program and test the EPROM chips. Also there are some other activities and projects that have more priority. However at least now i have all the components to use EPROM memory. Perhaps i can even us it with some other UV experiments.

 

Digital Testpen

 A week ago i received a cheap digital test-pen from china. I already mentioned in my mailbag post that i would post something about two small cheap upgrades. 

This cheap device can be used to test digital signals. it contains of a pcb with a wire as test pin and Dupont cables and comes in a sealed plastic bag. There exist several schematics to build these kind of devices yourself. However this was a cheap (almost) finished product on AliExpress.

I did two little cheap hacks to enjoy the use of this device even more. However first a photo of the back of the pcb to get a complete visual impression of the device.

As not all points always have Dupont connections i added male Dupont pins to small alligator clips. Using this alligator clips attached to the wires the testpen can also be used if no Dupont pins with power are available in the circuit you want to test. 

After soldering i even decided to remove the plastic of the male pin.

The second easy and cheap hack is using transparent heat shrink over the PCB to protect it. It can be done very easy and adds protection to the test pen pcb circuit. All you need to do is cut some transparent heat shrink tube at the appropriate size. Put it over the pcb and shrink it with a hot air gun.
If you want even more protection you can use a hot glue gun to first add a glue layer. For my use of this device i expect the heat shrink tube will be sufficient. 

Below you see the result: 

Mailbag_09aug2020

 Some days ago i received some interesting items from Aliexpress / China. Time for another mailbag blog post!

UV detection card

I did see this item in a YouTube video. It is a cheap card an can be used to detect UV light. I did not yet test it, however it seems useful to have for my experiments with UV leds and lamps and other experiments with optics, The mall picture show the backside of this card.

Digital test pen

On Aliexpress i found this cheap digital signal test-pen to test 5 and 3 volt digital signals.  I hope to post soon on my blog some hacks/little improvements.

Pen with conductive ink

In several articles and YouTube videos people experiments with electrical conductive ink are presented.
It looks that you can easy draw your electronic circuit on paper and glue with conductive glue your components. I found this conductive ink on Aliexpress and decided to give it a try.

I did not yet full tested the product. Perhaps i did buy a to cheap conductive ink pen as it was more difficult than expected. Before the ink started flowing i had to shake the pen and to move the pen over the paper several times. When shaping the pen you hear a little ball (?) moving in the ink reservoir.

After trying to write suddenly ink starts to come out of the pen. With my multi-meter i measured the resistance and it was not conductive. To get a conductive line i had to write the same line several times and dry the ink with my heater that i normally use for heat-shrink tube. (First I did not yet use it for real electronic experiments.

Lamp holder

This are cheap lamp holders for GU10 lamps. I ordered some as i want to replace some halogen lamps with GU10 led lamps. At the local hardware stores (Praxis or Gamma) i could not find lamp withe the same diameter as the current halogen lamps.

Temperature sensors

These three legged items perhaps look as transistor. However they are cheap smart temperature sensors (DS18B20 ) .Two wires are for the plus (+) and minus (-) and one wire is used for data transmission to a micro-controller.  Several of these sensors can be placed in parallel and the temperature of each sensor can be read individual as all sensor have an unique address.

Hand drill

This little tool is something i should have bought sooner. In the few days i have it now i used it several times. It has a little drill chuck for little drills. This way i can easy make little holes e.g. in plastic and do not need to use a fast rotating electrical dill or Dremel or punch a holes with other tools.

LCD

Received two LCD displays from China.
Plan is to use them with my FPGA('s).
Therefore soldered Dupont connector pins (See pictures below).
Expect that for playing with these displays and posting something about it will take more time than the soldering....

LCD 1602

LCD 12864

USB Microscope NeoPixel picture

Some pictures of a neopixel taken with my USB Microscope

What is a NeoPixel:

A NeoPixel is a small color led light with 4 connections.

Two points need to be connected to the power ( plus and minus ) One other connection is for an input control signal and the fourth connection may be used as output to connect to the next NeoPixel.

This way a lot con NeoPixels can be connected like a chain. The photos in this post are from a set of pre-soldered neopixels on a pcb where you can break out a small round pcb with one neopixel and the connections. This round led pixels can be used together with a micro controller (arduino, esp, .. ) in projects.

(this picture is NOT from the USB microscope but taken with my smartphone

The first input needs to be connected to a micro controller. The micro controller can send send a signal and control each individual led separate to set the color and brightness.

Microwave Radar Sensor RCWL-0516 -2- (led)

Motion detector with led 
This is the next post on this blog testing the RCWL-0516 sensor. This sensor uses a “microwave Doppler radar” technique to detect moving objects and has a sensitivity range of ~7 meters.
The sensor does NOT detect if someone is near , it can only detect movements!

A long time ago my first post was about using the Microwave Radar Sensor  RCWL-0516 with an Arduino Uno.

 

This cheap and interesting module has the following connections :

• 3V3  - Output 3V3 Regulated DC (100 mA)  This is 3V3 Output NOT input !
• GND - Ground 0 V
• OUT - Microwave Radar sensor output ( HIGH (3.3 V) motion detected/LOW (0 V) idle)
• VIN  - 4 to 28 volt input to power this module
• CDS - This pin can be used to disable detection. You need not to connect it. (Low= Disabled)

A 9 Volt battery was used to power the module. Be aware that after powering the module there is a delay (10 seconds) before the sensor is active.

Besides the CDS pin it is also possible to solder a light detecting resistor ( LDR ) in to the two holes below the RCWL-0516 text/logo. (On the other side of the PCB it is in the top-left square). When there is light on the LDR the Microwave Radar Sensor will not give a signal on the OUT pin.

In this post i describe recent tests using this proximity sensor without a micro controller. The photo's with the Dupont wires on the sensor connectors where from the previous post. This time i soldered pins to a sensor.

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1) In the first test i connected a "standard led" between the OUT and GND with a 220 ohm resistor. This is a simple configuration to test the sensor

2) As i also wanted to check if the circuit is on i also added a (red) led between GND and 3V3 

3) The next idea was using a laser led. The advantage of using a the laser is the very far distance of the laser beam can travel before projecting a dot. The laser light can travel further than standard WiFi, Bluetooth or 433MHz radio signal. On a distance of more than 40 meter you should be able to see if there was movement near the sensor. 

The disadvantage is that you need a line of sight and you can not check if the sensor is functioning as the laser is default off. I tested drivign a cheap laser led directly on the output. However it seemed not possible to drive directly a laser (at least not the small lasers i have) with this module. So direct driving a laser led was a failure. The laser led does light when connected between ground and 3V3 an option could be driving the laser indirect e.g. using a transistor, opto-coupler or relay.

4) I also wanted to do some tests to know if it is better leaving the CDS 'floting' or connect the CDS pin to a logic level.

A prototype perf board was used to create a development/test board for a real test environment. Using wires only would reduce space however it also would lose some flexibility. I did not want to order a PCB or use a breadboard.
Bottom right is the power connection. The switch is used to turn the battery power on/of. Jumpers where used to enable or disable parts of the circuit. I did not want to use a (more expensive) breadboard.
Different colors for the jumpers are used.

The red jumper is used to enable the 'power on' led

The yellow jumper is used to enable the yellow 'signal out' led (using a resistor) 

The white jumper can be used to connect CDS to GND.

Also additional pins an connectors where added to play and do (lateron) more experiments with this sensor.

The sensor pins from left to right (extended over the full lenght of the perfboard) are   

01 - CDS

02 - VIN 

03 - OUT

04 - GND

05 - 3V3  

Results: 

It is possible to direct derive a led with a small resistor) between the output pin and ground without a micro controller.

A battery powered board with a circuit  to test the RCWL-0516 was created and could be used to test the sensor.

Direct driving a small laser led was not possible. Perhaps indirect using a relay, transistor opto-coupler this is possible.

First test showed that motion at about 3.5 meter could be detected using this circuit.

Currently i can not yet decide if it is better to leave the CDS pin floating or connecting it to a logic signal. Both options seem to work. More tests need to be done to decide what is better. 

Some links about the RCWL-0516 sensor:

• https://www.electroschematics.com/get-started-microwave-radar-motion-sensor/
• https://github.com/jdesbonnet/RCWL-0516