Tech Blog

Recently we had a few customers asking about driving our DC gear motors with H-bridges, and specifically, whether they would need additional fly-back diodes for each transistor in the bridge. As it happens - you don't, and there are a few options that can be arranged 'for free' my some small modifications to the timing of the drive signals to the transistors in the bridge. What is Decay? Decay is the re-circulation of current within a motor driver that uses pulse-width modulation (PMW). The inductive nature of DC motors means that they will oppose any change in curr…

Our latest tutorial covers driving multiple LRAs from a single source We recently added a new tutorial for the M20-200 Haptic Feedback Evaluation Kit , which looks at driving multiple LRAs from a single source. Unfortunately, driving multiple LRAs at the same time is extremely problematic for a single haptic driver as many of the excellent features (such as auto-resonance) don't work when there are several LRAs connected in parallel or series. We cover this topic in full (including how to drive multiple ERMs) in this b…

The 132-100 with a capacitor for EMI suppression, and the PCB backpack equivalent Our larger DC motors commonly have terminal power pins, as opposed to SMD motors or ones with power leads. Whilst in some applications this can be a drawback, others appreciate the flexibility offered - bear in mind that larger motors have a much wider range of mounting considerations rather than simple surface mounting on PCBs or bulkheads. Often, motors are mounted in custom moulded plastics, which can be in locations relatively remot…

Many haptic applications, in particular wearables, face severe trade-offs in overcoming limitations in power supplies. A battery’s volume is directly related to a host of other desirable specifications, such as voltage, current, or capacity. For many designers, squeezing as much life out of their battery is one of their greatest challenges. In this blog post we’ll look at each of these limitations in turn before discussing one of the most common, but often unsuitable, battery choices. Challenges Faced Limited Voltage …

Intro When it comes to mounting motors, a common solution is to use adhesives or glue. Even some of our coin motors and LRAs come with special backing to help keep them in place. However, these adhesives need to be carefully selected as they can be damaging to the motor, causing reduced performance or even failure. This article serves to highlight some of the potential issues and methods for avoiding them to ensure optimal performance. What adhesives are known to cause problems? The most common culprit that we enc…

Incremental encoders are used in many different motor applications, where they can provide information on the motor’s speed or the shaft position. Normally, the output signal from encoder is at least one square wave, but most often it sends two square waves with their phase shifted at 90 degrees - known as quadrature. For a background on incremental encoders (and how they differ from absolute encoders) you can read our previous blog post , which includes a useful diagram. Encoders have specific number of pulses per revolution (ppr), …

The main complexity of BLDC motors is the need for specialised drivers to handle the electronic commutation, but is there actually a hidden advantage? BLDC motors have many plus points, including high endurance and a higher power-to-volume ratio than their brushed DC motor counterparts. However, some regard the need for additional drivers as a drawback - but with advanced driver ICs the user complexity is greatly reduced, and we can actually use them for relatively precise positioning control. Stepper motors are commonl…

N/L speed and Stall Torque on Motor Performance Graphs Our latest Application Bulletin covers a topic that our sales engineers are frequently covering with customers. In AB-032 we cover the the inter-dependent relationship between drive voltage, output speed and motor torque. You can read the full bulletin for an explanation of the fundamentals, but in the spirit of offering practical advice on our blog and monthly new letter, here is a section regarding what we can do to alter the motor performance to meet your …

At the end of last year, Doug wrote a blog post about the basics of reversing DC motors. Since a number of customers have asked us to advise about this recently, we expand upon this topic with some practical tips. If you’re not interested in the theory, skip to the end for our practical conclusions section. Are DC motors Reversible In short, yes. If you reverse the voltage to the motor, it will rotate in the opposite direction. The reasons for this are given in the earlier blog post ARE DC MOTORS REVERSIBLE ? But we n…

The Haptic Shield uses a 3.5mm audio jack We recently published a new tutorial for our Haptic Feedback Evaluation Kit that explores how to play music or other audio signals on a vibration motor or LRA. Using the great new "Audio-to-Vibe" feature in the DRV2605 and the 3.5mm audio socket on the Haptic Shield, you can easily experience meaningful vibrations alongside your audio output. This tutorial shows you how to access the feature in our Engineering Mode (and of course points you in the direction of the required f…