The Unlicensed Bands 433MHz 868MHz 915MHz Antenna Wire antenna A very good antenna to use for maximum range. Use a length of wire (or a PCB track) 1/4 wave length (e.g. 172mm for 433MHz). The optimum is to use the wire straight, but it can also be bent into a 'L 'or 'U' shape if necessary […]
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Audio Beat Detect
A working audio beat detect circuit for a microcontroller using a microphone input This circuit uses a digital pot to allow the microcontoller to automatically adjust the gain of the circuit to suit the ambient audio volume, but you could replace this with a standard pot if this isn't needed. The low pass filter is […]
Floppy Drive 4 pin Power Connector
Typically used for 3½ floppy disk drives. Called a "Berg" connector. AMP EI Series part numbers: AMP / TE Connectivity 171822-4 – Cable socket AMP / TE Connectivity 171825-4 – Vertical PCB header AMP / TE Connectivity 171826-4 – Right Angle PCB header Pin Name Color Description 1 +5VDC Red +5 VDC 2 COM Black Ground 3 COM […]
USB Power Requests
The Power Request Made within the USB CONFIG DESCRIPTORs. You can have more than one with different power requests, but host devices may not support dealing with multiple configurations. General Power Availability A device that wants to be able to function on all systems and hubs should request 100mA max. Multiple Power Configurations One solution […]
Brushed DC Motor Drives
PSU Votlage A motor will only go as fast as you have volts to apply (with no loading taken into consideration), so whilst you can run a DC motor and its drive at below its rated voltaged, the maximum speed possible will reduce. This can usually be calculated from a motors RPM/V specification and this […]
Conductive Rubber Button PCB Pads
An example of gold plated pads from a Fluke multimeter, one of which has a LED which illuminates the button:
Innovation Vouchers
An Innovation Voucher provides funding so that your business can work with an external expert for the first time, gaining new knowledge to help your business innovate, develop and grow.
Via’s
Via Current Rating A general rule of thumb for typical via's (say 0.5mm) passing high currents between layers is to allow 0.5A nominal per via. Bigger hole sizes increase this rating with the larger surface area of the plating through the hole, but for high current connection more smaller vias can beneficial if your copper […]
E-Ink
Its been a long time coming for E-Ink displays to be available for general use (i.e. for customers not committing to 1 million units a year!). These distributors are carrying them: www.craftdata.co.uk Temperature Range More limited than for LCD screens. An operating temperature range of 0º to +50ºC seems to be typical for an E-Ink […]
Why Are PCB’s Green?
A PCB's colour is given by the solder mask coating and actually PCB's can use one of many colours these days. The reason green is still often used is probably a combination of its always been down that way and because green solder mask is actually a very good balance of being OK on the eyes […]