Maker LED Flasher

Introduction
This blog details a prototype flasher circuit board for a school Maker community. The board design is built to accommodate through-hole and surface mount components. Featuring two component mounting styles allows the board to serve multiple uses in a school environment.

Dual LED Flasher PCB

Circuit
The circuit in the blog uses a well-worn astable LED flasher design made with discrete components. A transistor pair, wired in a common emitter configuration that drives a total of four LEDs were used. As a DC 9 V battery powers the circuit, more LEDs could be added to the design to interest young Makers.

 

LED Flasher Circuit

For the feasibility review of the prototype by the Maker community, both circuits were placed on one side of the circuit board. A single switch (surface mount) was used to control power to the through-hole and surface mount sections.

PCB
An ABS enclosure from a local supplier was initially chosen for the prototype. PCB dimensions and the mounting hole locations for the circuit board were extracted from the ABS enclosure.

Components for the flasher circuits were placed on the top layer of the board. The battery connector was relegated to the bottom layer allowing a battery to be placed inside the ABS enclosure. Routing of the board used two copper layers.

Dual LED Flasher Routed PCB

3D Printed Case
With many Makers communities having 3D printers a printed enclosure was created based on the commercially available product

3D Model of Plastic Case

The Fusion 360 and STL files are located at the end of this post.

3D Printed Plastic Case

Making
The image below shows the through-hole portion of the circuit board after being populated and partly soldered by a school student. 

Half Populated LED Flasher Board

All the through-hole LEDs and capacitors were taken from salvaged components.

To hold the circuit board in position, round head metal self-tapping screws, 3 mm between crests, 7.5 mm in length were utilised.

The surface mount portion of the board was hand populated as a second step for this blog as can be seen in the image below.

Fully Loaded Flasher PCB in 3D Printed Plastic Case

The video below shows the through hole portion of the flasher board operating.

The second image shows the surface mount section in operation during testing.

Captures from Circuit
For those Maker communities interested in checking the circuit waveforms with a oscilloscope, below are some captures taken from the transistor collector and base connections.

Voltage Measured at Transistor Collector

Voltage Measured at Transistor Base

Summary
The LED flasher detailed in this blog was published as an example for Maker communities. Available for download below is the artwork for the circuit board and the file for a suitable 3D-printed case.

Flasher Schematic

Flasher PCB

Flasher Gerber

Flasher PCB Bill of Materials

3D Case in Fusion 360

3D Case as STL*

* If the plastic case is used, 4 x round head metal self-tapping screws, 3 mm between crests, 7.5 mm long may be required.

Altium Parameter Set Example

Introduction
This blog looks at other uses for the parameter set that is available when drafting in Altium Designers’ schematics.

Example of Altium Schematic with a Parameter Set Rule

Parameter Set Requirement
An engineering pack is commonly used to convey coherent and clear manufacturing information to a production company responsible for either printed circuit board (PCB) manufacture or assemblies (PCA). Some of the information or parameters contained in the engineering pack will vary vastly between companies.  For example, some components used on a circuit board may be specified to meet automotive or military grades. Other requirements may relate to the approval of component suppliers, the custom design of a component, or factory programmed to list a few. Whilst other companies may require components traceability if certain regulations or requirements such as PSE, IEC or ANSI are needed.

The component part number may usually contain sufficient detail for the requirements detailed in the above section however in other cases, additional product information may need to be shared with the manufacturing partner.

Parameter Set Use
This blog leans on the schematic parameter set available in newer releases of Altium Designer for providing additional component information to the production company. While pushing details into the parameter set may not be considered a clean integration compared to the Altium component database, changes can be made to a project without modification to the library. Details contained in the parameter set can still be reflected in reports such as the bill of materials (BOM). This solution may be helpful for projects where minimal business investment in the project is warranted but project control using a design tool is essential. 

Parameter Set Example
For the example in this blog, the Altium Designer project ‘Mini PC’ (courtesy Altium) will be used.

Altium Example Project - MiniPC

Target Schematic Page from Altium Example Project - MiniPC

Assume for the example in this blog that the jack and relay were hand populated. The circuit board loader in this example required documentation for components that required hand population.

Example Schematic Page with No Parameter Set

A blanket rule was placed over the power jack and relay schematic components.

Example Schematic Page with With Parameter Set

A parameter set rule was added to the blanket rule on the schematic, with the custom parameter ‘Hand Population'.

Example Altium Parameter Set

An additional custom parameter set for a ‘Listed Part’, was added to illustrate that multiple parameters could easily be added to the schematic as required.

Parameter Set in Bill of Materials
When generating the Bill of Materials (BOM) in Altium, details from the schematic parameter sets are available in the BOM Properties ‘columns’.

Altium BOM using Parameter Sets

Viewing the parameter set information in the BOM generated by Altium is possible by enabling the required parameter listed in the columns section of the BOM manager. This allows customisation of the various board fabrication or assembly houses.

Extract from Altium MiniPC Project with Parameter Sets

Pictured above is a portion of the generated BOM when the ‘Hand Population’ and ‘Listed Part’ parameter set entries were enabled.

For Altium projects that have several variants, components in schematics are likely to be controlled using the variants manager. Components are marked as fitted or not fitted. When a parameter set is used, the fitting of components with parameter sets in the BOM should be reviewed.

HPM D817SLIM Repair

Introduction
This short blog details the repair of an HPM main-powered digital switch timer, model D817SLIM. The fault symptoms are a blank LCD which does not restore even after the timer is plugged back into the mains.

HPM D817SLIM Mains Digital Switch Timer

Opening the Digital Timer
Disclaimer: Repair of any mains-rated electrical equipment should be conducted by qualified personnel. The information provided in this blog is for reference purposes.

The mains-powered timer (unit) had not been powered for several years and the LCD that displays the time and timer functionality was blank. Connecting the unit to the mains did not restore the operation of the LCD.

To open the unit, there are two plastic screws on the rear of the unit. The screws appear to be a Y-wing or a variant of that screw. A 2.4 mm wide flat blade was found fit the head pattern and the screws were removed. The two-piece plastic case uses internal clips so the same screwdriver can be used to unclip the case halves. There are circuit boards on either side of the plastic cases.

Internals of HPM D817SLIM Mains Digital Switch Timer

Dead Battery
Upon opening the case, a small Ni-MH battery with corrosion or leakage was visible on the circuit board. The part was identified as a Troily 1.2 V 80 mAh Ni-MH battery.

Troily 1.2 V Ni-MH Battery

Instead of replacing the battery, it was decided to use a standard electrolytic capacitor. If this unit was to be used in an area with frequent and long interruption to mains power, a battery replacement would be advised instead of the capacitor.

To remove the circuit board with the battery, two small Philips screws were removed.

Removed Troily Battery from HPM Circuit Board

Battery Replacement
The battery was then unsoldered and replaced with a 1000 uF 25 V electrolytic capacitor. Since the operating voltage of the mains timer circuit is less than 5 V, a 6.3 V capacitor with a larger capacity could likely be used. Testing showed that with a 1000 uF electrolytic capacitor, the switch timer remained powered for approximately 6 minutes after a mains failure.

HPM D817SLIM Mains Digital Switch Timer with Capacitor

Other options to repair the unit, such as replacing the Ni-MH battery with a similar type or using a supercapacitor may be possible.

240 V AC Mains Adaptor for Rachio 3 Smart Controller

Introduction
This microblog details the process of fitting a 240 V AC mains transformer to the Rachio 3 outdoor enclosure. The solution does not require a separate step-down transformer.

Rachio 3 Smart Controller Enclosure with 240 V AC Mains Transformer

 Details
The Rachio reticulation controller is shipped with a 110 V AC to 24 V AC transformer (adaptor). While the provided transformer alone is unsuitable in regions where the main supply grid is a different voltage, there is an alternative transformer that fits inside the Rachio weatherproof enclosure.

The 240 V AC to 24 V AC transformer is available from suppliers such as Amazon, Altronics or the BourneSuperStore.

PowerTran 24 V AC Transformer Plate. Altronics M 9381

Fitting

Disclaimer: The voltages present in this post are 240V AC. Care and steps should be taken to prevent electrocution. Wiring should only be performed by experienced persons.

The previous mains socket was removed from the Rachio outdoor enclosure to fit the alternative transformer. The socket assembly is a snap design that can be removed using a screwdriver.

Mains Socket from Rachio Weatherproof Enclosure

A separate double-insulated mains cable was provided to the Rachio enclosure through a 25 mm cable gland for the mains supply.

Rachio Weatherproof Enclosure with Cable Gland

The alternative transformer was supplied with a moulded mains plug. Mains termination was made by shortening the transformer cable and then connecting it to the outside mains cable. The existing section in the external enclosure was used for termination.

Mains Cable Termination in Rachio Weatherproof Enclosure

The transformer was placed in the upper left corner of the enclosure.

Installed 240 V AC to 24 V AC Mains Transformer

Following the installation of the alternative mains transformer, the process for wiring the Rachio controller was followed.

Rachio 3 Smart Controller Mounted in Weatherproof Enclosure

Adafruit 4435 PCB Shape and Dimenstions

Introduction
This microblog provides the dimensions and clearances required when a circuit board is used with an Adafruit DIN rail holder circuit board holder, part number 4435.

Adafruit DIN Rail Board Holder (Courtesy Adafruit)

Circuit Board and Keep Out Dimensions
The dimensions provided in the Adafruit 4435 datasheet are precise for the circuit board shape however the information does not include any other clearances. For component placement on the circuit board, an area of 46.6 mm x 70 mm is available. The rails that hold the circuit board consume some board space. 

The purple line shown inside the object below (Keep Out Area) shows the area that can be used for components or hardware.

Adafruit (4435) Circuit Board Dimensions and Usable Board Area

The distance between the bottom side of the example circuit board and the DIN rail holder is approximately 8 mm (assuming a 1.6 mm board). The separation between the faces is closer to 8.5 mm although factors such as thermal expansion and circuit board warping should be taken into account.

Adafruit (4435) Printed Example Circuit Board Showing Clearance to Case

Keep Out Area Validation
In each corner of a example circuit board, at the edge of the keep-out region, an extruded feature was placed.

Circuit Board Positioning Feature

A 3D model of the circuit board was printed. For validation testing, this circuit board was fit into the Adafruit DIN rail holder. Using a feature on the printed model allows easy checking of tolerances, especially between horizontal and vertical faces.

Example 3D Printed Circuit Board in Adafruit DIN Holder (4435)

 
Downloads
The files and models provided below are without the raised feature mentioned in this blog.

Circuit Board Shape and Component Keep Out for Adafruit 4435 (DWG)

 

Circuit Board Shape for Adafruit 4435 (STEP)

 

EPEVER MPPT to Elfin EW11A Adaptor Circuit Board

Introduction
This blog follows on from a previous post relating to WiFi communication with an EPEVER MPPT. In this post, a DIN rail mount adaptor was created to power the Elfin EW11A (WiFi to RS485) device.

EPEVER MPPT to Elfin EW11A Adaptor

Wiring
In a previous post, the connection to an EPEVER MPPT was tested using an Elfin EW11A that was set up for station-mode WiFi operation. The test wiring described in this post was clumsy so a permanent fixture was designed.

DIN Rail Mount Solution
The connections required for the circuit board between the MPPT and EW11A were already established and tested. To power EW11A, a Texas Instruments DC-DC buck converter was selected. 

To mount the circuit board containing the aforementioned parts and rather than spinning up a 3D printed part, Adafruit’s DIN rail mount was used.

Schematic
The RS485 schematic connection between the MPPT and EW11A using RJ45 connectors is shown below.

Circuit Board Connections for EPEVER MPPT to Elfin EW11A

In the power supply circuit shown below, a reverse polarity protection diode is at the front end of the design. Following the polarity diode is an optional transient diode (TVS) clamp and PI filter. Bypassing the filter is possible using the two optional bypass resistors which were added in revision 1 of the circuit board. Powering the EW11A is a DC-DC buck converter, notably the Texas Instruments LMR14203; no linear regulators here. At the time of writing the lead time of TI regulators exceeds a year so some equivalents could be the LMR16006X, LMR16006Y or MP2451DJ; these alternatives should be reviewed for compatibility.

Circuit Board Connections for Elfin EW11A Power Supply

For the sundry items on the board, a power LED was included but to conserve power this device could be unpopulated or the series current limiting resistor increased.
To reset the EW11A, a pair of circuit board pins were provided on the circuit board. Shorting the two pins provided on the circuit board will perform the reset.

Circuit Board (PCB)
The board shape was designed using the dimensions shown on the DIN holder datasheet (Adafruit website). The fitment of the circuit board in the DIN holder was accurate, although the placement of components near the edge of the circuit board was tight. A larger keep-out for the components from the edge of the circuit boards was included in the next revision of the board.

EPEVER MPPT to Elfin EW11A Circuit Rev 1 Board Top Layer

EPEVER MPPT to Elfin EW11A Circuit Board Rev 1 Bottom Layer

Testing
The populated circuit board was powered with DC 24 V and load-tested. No temperature, climate or similar tests were performed.

With no load, the DC output voltage was 5.02 V with a quiescent current of 5 mA (LED). The output voltage dropped to 4.98 V when the EW11A was powered by the regulator. Greater than DC 6 V should be provided to the DC-DC converter for stable operation.

EPEVER MPPT to Elfin EW11A Circuit Board Rev 0 Bottom Layer

A functional soak test of the circuit board over a 24-hours showed no issues. No dropped packets were detected by the virtual COM port application "HW Virtual Serial Port", version 3.1.2.

Downloads
Listed below are the MPPT to EW11A adaptor schematics, circuit board Gerber files and project Bill of Materials. The blank circuit boards can be made available at PCB Way using their Shared Projects option. The supplied schematic and Bill of Materials are for a fully populated circuit board.

Disclaimer: Please note that revision 0 of the the circuit board was tested in this post; no functional changes relating to the MPPT or EW11A connections were made in revision 1 of the circuit board.

Elfin to EPEVER Rev 1 Schematic

Elfin to EPEVER Rev 1 PCB

Elfin to EPEVER Rev 1 BOM (Full) Excel

Elfin to EPEVER Rev 1 Gerber and NC Drill