Intro to High-voltage Battery Disconnect Switches

This article introduces high-voltage battery disconnect switches, where transistors have replaced the old-fashioned relays. Electric cars currently on the market use 400 and 800 V batteries with nominal currents above 200 amperes, which could be lethal if this high voltage and current were connected to the chassis or any conductive part of the car. To prevent such … Read more

Adjustable triangle/sawtooth wave generator using 555 timer

The circuit works due to the fact that voltage increases or decreases linearly when a constant current flows into or out of a capacitor. If we manage to charge and discharge the capacitor with the same constant current, then the voltage of the capacitor will become a triangular wave; that’s the crux of this circuit … Read more

Gallium Semi launches GaN transistor lineup for 5G

Gallium Semiconductor has unveiled its portfolio of RF GaN transistors for 5G infrastructure, aerospace, defense, industrial, scientific, and medical applications. The company’s bare die and discrete GaN-on-SiC HEMTs operate up to 8 GHz at various power levels. Key product highlights include: Known good die of GaN devices optimally designed for low thermal resistance and ranging … Read more

Sneaky peak: sneaky feedback paths that de-stabilize an otherwise stable feedback loop

I have long held to the belief that electrons are smarter than people. Even the best engineers can fall prey to subtleties that electrons will readily act upon, especially when it comes to finding sneak feedback paths that can really screw up an otherwise stable feedback loop. We look here at a case study. There … Read more

Linearized portable anemometer with thermostated Darlington pair

This self-heated constant-temperature-delta transistor anemometer is cheap, rugged, and sensitive.  It relies on the relationship between airspeed (AF) and thermal impedance (ZT = oC/W) of a heated air flow sensor as shown in the formula below for a 2N4401 transistor in TO-92: ZT = ZJ + 1/(SC + KT √AF ) where:ZJ = junction-to-case thermal … Read more

Electronics for Kids: Part 9 – Simple Transistor Experiments

On a physical level, a transistor’s internal functioning is very complex, but, in practice, using it in some simple experiments is quite easy and affordable for everyone. The transistor A transistor allows to create very simple but useful devices such as lamps that turn on automatically when it gets dark, or acoustic signals that emit … Read more

Getting rid of the diode voltage drop in a charge pump circuit

Nowadays microcontrollers and microprocessors are powered with a DC voltage of 3.3V (even 2.5V, or 1.8V, etc.). So, the well-known forward voltage drop of diodes really becomes an issue for many electronic circuits such as the AC/DC bridge, HF detector, and charge pump to name a few. Let’s talk about a classic charge pump circuit: … Read more

Self-heated Darlington transistor pair comprises new air flow sensor

Among the many methods available for air flow detection, self-heated thermal flow sensors are simple, cheap, rugged, and sensitive. They rely on the relationship between airspeed (AF) and thermal impedance (ZT = oC/W) of a heated sensor as shown in the empirical thermal impedance formula below.  It quantitatively relates junction temperature rise, power dissipation, and … Read more

Dual N-channel JFET lowers noise in precision instrumentation and sensors

The LS844 monolithic dual N-channel JFET from Linear Systems provides low input capacitance, substantially reducing intermodulation distortion. Targeting precision instrumentation and sensor applications, the LS844 offers a combination of high transconductance, low noise of 2.5 nV/√Hz typical at 1 kHz, and low input capacitance of just 3 pF typical and 8 pF maximum. Constructed by … Read more

N-channel trench MOSFETs eases thermal management for wearables

With their low on-resistance, Nexperia’s 12-V and 30-V N-channel trench MOSFETs minimize energy losses and increase efficiency. The 30-V PMCB60XN and PMCB60XNE come in ultra-compact wafer-level DSN1006 (SOT8026) packages, while the 12-V PMCA14UN is housed in a DSN1010 (SOT8007) package. Nexperia reports that the MOSFETs’ RDS(on) is up to 25% better than competing devices. Simplified … Read more