Martin Harizanov writes, “The comments to my last blog post got me thinking if I had chosen the right RFM channel at home, obviously if the channel is noisy that directly affects reception and increases the error rates. I use the default 868Mhz setting for the RFM12B/RFM69s at home and decided to check if the channel […]
Author Archives: DP
PCB inspection stand for Chinese magnifier
Tom Keddie writes, “On the last hacker camp I picked up a magnifier with HDMI output on Taobao (or more expensive but no airfare needed 14MP HDMI HD Microscope USB Industrial Camera 180X C mount Lens Stereo Stand) I find myself needing to peer into and under packages a lot, I got sick of holding […]
App note: Combining GDTs and MOVs for surge protection of AC power lines
Another circuit protection from power surges/spikes application note from Littelfuse. Link here (PDF) AC power line disturbances are the cause of many equipment failures. The damage can be as elusive as occasional data crashes or as dramatic as the destruction of a power supply, computer terminal, or television set. Power line disturbances go by many […]
Free PCB Sunday: Pick your PCB
We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will […]
App note: Circuit protection for Lithium-Ion and lithium polymer rechargeable battery applications
Adding secondary circuit protection to ensure safety when using Lithium-Ion and Lithium polymer batteries discussed in this app note from Littelfuse. Link here (PDF) The introduction of portable devices with advanced features and the demand for longer run times and has resulted in innovations in the battery technologies used for portable applications. The latest generation […]
Free PCB coupon via Facebook to 2 random commenters
Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three […]
Breaking a Teensy U2F implementation: why you shouldn’t write your own crypto
Aidan (a.k.a. makomk) writes: A while ago, Google created a two-factor authentication scheme called U2F. The general idea is as follows. You have a little USB dongle that you can register with sites. When you enable U2F on a site, the dongle gives that site a public key and a key handle, and that dongle […]
A development board for the STM32F042 TSSOP package
Andy Brown designed a development board for the STM32F042 in the TSSOP20 package: Development board features USB. The 042 series supports USB and although 32Kb is not a lot of space to include a USB driver and your application logic it does make sense to hook up those USB data lines and thereby enable USB device development. […]
Search Github projects by component, find design references
Search Github hardware by component to find examples and references for your next project. Big schematic and PCB previews mean quick and easy browsing without opening a CAD program. TomKeddie first mentioned this idea at Hacker Camp Shenzhen, and later in the forum and on WeChat. Tom generously shared his scraping/search method. Eagle 6+ […]
RFM69_ATC: Automatic Transmission Control
Felix of LowPowerLab writes: There is now a new extension to the RFM69 library. It’s called RFM69_ATC aka Automatic Transmission Control. Many thanks to Tom Studwell who implemented this and shared it in the forum. The basic idea behind this extension is to allow your nodes to dial down transmission power based on the received […]
Analog Devices AD587KN 10V reference
SteelCity Electronics published an article about Analog Devices AD587KN 10V reference: I recently got hold of an Analog Devices AD587KN high precision 10.000V reference chip. This model of chip has an output value of 10.000V ± 5mV (that is, an output value of 9.995V to 10.005V) straight out of the factory. A voltage drift of […]
#FreePCB via Twitter to 2 random RTs
Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week: Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch […]
Repairing the TUNE capacitor on the Heathkit HL2200 (SB-220) amplifier
KA7OEI did a repair on his amplifier. He documented the whole process on his blog: Earlier this year I picked up a Heathkit HL2200 amplifier (the newer, “brown” version of the SB-220) at a local swap meet for a reasonable price. What made it particularly attractive was that it not only had a pair of […]
Teardown & analysis of a Keysight InfiniMax III N2802A 25GHz active probe
A teardown & analysis of a Keysight InfiniMax III N2802A 25GHz active probe from TheSignal Path: In this episode Shahriar takes a close look at one of Keysight (Agilent) InfiniMax III active probes. The model N2802A offers 25GHz of analog bandwidth, 17.5pS of rise time and a total differential input capacitance of 32fF at 10k-Ohm […]
Dynamic microphone preamplifier
Dilshan Jayakody published a new build, a microphone preamplifier: This is single chip dynamic microphone preamplifier which is design to drive using commonly available 12V single rail power supplies. Preamplifier in this article is build around popular NE5532 dual low noise operational amplifier IC and this preamplifier is specifically constructed to drive professional 600Ω dynamic microphones. This […]
App note: Transient suppression devices and principles
App note from Littlefuse on how do transient suppression devices protect electronic circuits. Link here (PDF) There are two major categories of transient suppressors: a) those that attenuate transients, thus preventing their propagation into the sensitive circuit; and b) those that divert transients away from sensitive loads and so limit the residual voltages. Attenuating a […]
Free PCB Sunday: Pick your PCB
We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will […]
App note: An overview of electromagnetic and lightning induced voltage transients
Application note from Littelfuse on sources of transient voltages that can induced in electronic circuits. Link here (PDF) This Note is an overview of the sources and nature of various transient overvoltages, and the problems that may result. Transients in electrical circuits result from the sudden release of previously stored energy. This energy can be […]
App note: AN-42 IC provides on-card regulation for logic circuits
This application note (PDF!) from TI provides on-card regulation for logic circuits: Because of the relatively high current requirements of digital systems, there are a number of problems associated with using one centrally-located regulator. Heavy power busses must be used to distribute the regulated voltage. With low voltages and currents of many amperes, voltage drops in […]
Radio thermostat CT-50 review and install
Felix of LowPowerLab writes: I mentioned before that there’s added support for HTTP requests in the gateway interface. That allows using things like wi-fi thermostats, and this story is a review of how I did just that. I wanted to integrate the home thermostat into the Moteino IOT Framework Gateway and be able to control […]