Opto V

[Rolando Kumar]

TheArris ESCs have capacitors and are opto-isolated, which is generally a good feature for larger drones (or drones with long wires). This is because the DC power lines are prone to large voltage spikes from the line inductance. During rapid throttle changes, the DC lines see large current changes which cause the line inductance to create magnetic fields that oppose the changing current. This causes problems with the rising current as the current lags the voltage, and the capacitors make up for the lagging current by supplying the line with the little bit of energy they have. And when the current is decreasing, the line inductance forms a magnetic field that tries to fight the decreasing current. This creates a voltage spike that can damage unprotected circuitry. Wire inductance increases as the wire gets longer, so that is why it is generally good practice to try to make your ESC input wires short.

Both brands have very good hardware, but are more expensive than other brands. I think T-motor Alpha ESCs are slightly better, but KDE will soon have CAN communication for ESCs of this size, which will be nice.

The downside of these brands is that they use proprietary ESC firmware, which means no BLHeli, which is probably the best ESC firmware out there for multirotors. But I use KDE and T-Motor because I build drones for customers and the hardware needs to be robust; the high-performance benefits of BLHeli are not really relevant to agriculture and survey drones.

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I'm trying to make a fully isolated circuit, and am having a problem with the communications. I intend to use Serial as communication at 9600 bps (slow but fast enough and easy to implement), and am trying to get this to work across optocouplers. Not much luck so far using this circuit:

I'm using PC817 optocouplers, rise/fall times said to be 3-4 s, and the data sheet shows that 10 kHz should be no problem. I've tried the latter with my scope, and it kinda works but I'm not getting anything near a clean 10 kHz block wave out. So I strongly suspect my optos are too slow for this. I know there are super fast optocouplers out there that can do 100 kHz I2C signals, but they're really expensive.

I learned a bit more about optocouplers now Thanks for the reactions.

I've decided to go for the 6N137 (edited) - unfortunately twice the size (DIP-8) but it looks like it will do the job just fine, as long as I make sure there's a 5 mA drive through the LED.

Me too! I went through the same learning curve. I am actually quite surprised how slow some opto couplers are, but never mind. I don't know the 6N139, I had to read a lot of data sheets before deciding on the TLP2962.

Sorry, that should be the 6N137 - a logic gate based optocoupler, seems to be quite similar in general design to the TLP2962. One major difference is that the 6N137 has a NAND gate and comes with an enable pin, while the TLP2962 has a NOT gate.

Its due to the semiconductor physics - optimum light sensitivity is not the same as optimum speed.

The first would like slow recombination times so the charge carriers actually get to be used for

transistor action before they recombine, the latter fast recombination so they go away once the light stops.

Simple photo-transistor based opto couplers are aiming for the transistor action gain to make up for

the substantial losses in the IR LED and the optic pathway, so they tend to go for highly sensitive

(slow) phototransistor.

This replacement opto-wheel is used on the Genie model garage door openers listed below. This opt-wheel normally needs replaced if your garage door opener is short traveling in both directions (open and close), in the excess of 6 inches at a time then stopping.

Need assistance? We are here for you! We offer a wide range of customer support options including contact by phone or email, web chat services with a live agent, and a robust support section also located on our website. All customer care teams and services are based in the USA.

Drop-in replacement for traditional optocouplers. Our opto-emulators include diode-emulator inputs and transistor outputs that transmit analog data in applications such as power supply feedback loops.

Address your isolation challenges with our reliable and affordable isolation technology. Through our proprietary isolation techniques, you can exceed isolation standards without compromising performance. Head to our isolation technology page to learn how to Increase safety with higher-reliability isolation at a lower system cost.

Opto 3 click features two pairs of normally opened, high-quality solid-state relays labeled as TLP241A, by Toshiba. The TLP241A is an optically isolated solid-state relay (SSR), featuring an integrated IR LED and two output MOSFETs. The output stage does not have any electrical contact with the input stage; it is activated by infrared light, produced by an integrated IR LED. This allows reinforced galvanic isolation between the input and the output stage. The output stage can sustain up to 40V while OFF. When activated, due to a very low RDSON of the integrated MOSFETs, it can conduct up to 2A of current.

The TLP241A are able to effectively replace traditionally used mechanical relays, bringing up the full set of inherited benefits: virtually unlimited number of cycles since there are no moving parts that would wear off, no bouncing effect on the output contacts, high resistance to mechanical shock and environmental influence, low current required for the activation, constant resistance since no carbon and rust can build up on contacts, there is no sparking or electric arc forming while operated, compact size, higher isolation voltage, and so on. However, unlike optocouplers (similar devices which are designed for much lower currents and voltages), SSRs are not designed to be used as signal line isolators. SSR typically has a slow signal propagation time. Still, it can be used for various communication protocols which use lower data rates, including UART/RS232, 1-Wire, and similar.

Depending on the development board you are using, you may need USB UART click, USB UART 2 click or RS232 click to connect to your PC, for development systems with no UART to USB interface available on the board. The terminal available in all MikroElektronika compilers, or any other terminal application of your choice, can be used to read the message.

Without the feedback winding, transformers may be designed for optimal coupling, best efficiency, smallest size and lowest cost. Coilcraft offers a variety of off-the-shelf transformers that have been optimized for these converters and designed for the most common output voltages and output power up to 24 Watts.

Controllers for no-opto flyback topology isolated converters are offered by several major IC manufacturers and are becoming increasingly popular for wide-range input-voltage, low-power, isolated converters across a variety of applications.

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Spatiotemporal control of brain activity by optogenetics has emerged as an essential tool to study brain function. For silencing brain activity, optogenetic probes, such as halorhodopsin and archaerhodopsin, inhibit transmitter release indirectly by hyperpolarizing membrane potentials. However, these probes cause an undesirable ionic imbalance and rebound spikes. Moreover, they are not applicable to use in non-excitable glial cells. Here we engineered Opto-vTrap, a light-inducible and reversible inhibition system to temporarily trap the transmitter-containing vesicles from exocytotic release. Light activation of Opto-vTrap caused full vesicle clusterization and complete inhibition of exocytosis within 1 min, which recovered within 30 min after light off. We found a significant reduction in synaptic and gliotransmission upon activation of Opto-vTrap in acute brain slices. Opto-vTrap significantly inhibited hippocampus-dependent memory retrieval with full recovery within an hour. We propose Opto-vTrap as a next-generation optogenetic silencer to control brain activity and behavior with minimal confounding effects.

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