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  • 3.3V Mod for Ultrasonic Sensors (prepare HC-SR04 for 3.3V Logic on ESP32/ESP8266, Particle Photon, Etc.)

    Here is a reseller for the "+" version. Look at the parts layout on the PCB. I have some of these and some of an older type.https://www.openimpulse.com/blog/products-page/product-category/hc-sr04-ultrasonic-distance-sensor-3-3-v-5-v-compatible/I think the plan might be to test them. Also maybe measure the operating current and see if it is 3ma or 15ma.

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  • 3.3V Mod for Ultrasonic Sensors (prepare HC-SR04 for 3.3V Logic on ESP32/ESP8266, Particle Photon, Etc.)

    "Even if the sensor's complete power consumption of 15mA were to go through that pin" It does NOT work that way. If you placed a low enough value resistor from echo to ground the unit would draw more than 15ma. You could likely get it to draw 20. Try "Ohm's Law". Let's assume the tiny chip's output pin can supply 1 mA (0.001 A) before it burns up. At 5 volts, the resister that draws 1ma is r= 5.0/0.001 Ohms or 5000 ohms. So long as the resistors add up to over 5K you'd not blow the part. But now the HC-SR01 is not long drawing 15ma from the power supply it is drawing 16ma. the 5K load on the output has caused a jump in power consumption. So the power consumption of the device has nothing to do with choosing a resister. What if you used a 50-ohm r...

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    "Even if the sensor's complete power consumption of 15mA were to go through that pin" It does NOT work that way. If you placed a low enough value resistor from echo to ground the unit would draw more than 15ma. You could likely get it to draw 20. Try "Ohm's Law". Let's assume the tiny chip's output pin can supply 1 mA (0.001 A) before it burns up. At 5 volts, the resister that draws 1ma is r= 5.0/0.001 Ohms or 5000 ohms. So long as the resistors add up to over 5K you'd not blow the part. But now the HC-SR01 is not long drawing 15ma from the power supply it is drawing 16ma. the 5K load on the output has caused a jump in power consumption. So the power consumption of the device has nothing to do with choosing a resister. What if you used a 50-ohm resistor? It would cause the device to consume a total of 115 mA and likely fail to do to some internal heating. The resister is not determined by the power consumption but the other way around, the resister strongly influences the power consumption and therefore you want the value to be hight.Your resistors are close the about the best values are given but the reasoning was wrong.People were questioning the value. The best answer is to calculate the answer. Answer: You have placed and about, roughly 1mA load of the the chip. That is likely OK Now lets computer how many watts Wats is i^2 * r. Assume a 5K resistor and 1ma current: 5000 * 0.001 * 0.001 = 5 milliWatts So any resister you happen to have will work even a 1/8thWatt would be an order of magnitude oversized.You have the right answers but the answer was maybe arrived at by a correct guess based on experience. Better to get out an old envelope and check

    Many HC-SR04 units can run fine on either 5.0 volts or 3.3 volts. They are sometimes sold as "HC-SR04+" parts but I never see the "+" printed on the parts. Yours looks like the duel 5/3.3 volt part.If you have one of these simply connect the Vcc to 3.3 volts and it will work. But perhaps you get better range with 5 volts? I don't know

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  • albertson.chris commented on ThomasH358's instructable Battery Powered Tube Amplifier6 months ago
    Battery Powered Tube Amplifier

    This is not a video but really good and easy to understand. He puts much of his material online for free but you can buy books too if you want more. But the online stuff is enough so that you can design small amps or at least read and understand the schematic.http://www.valvewizard.co.uk

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  • A Practical Guide to FDM 3D Printing Gears

    Great collection of information. One question: Typically when I start designing something to transmit power I know the speed and torque that is required. How can I predict the maximum torque a gear will transfer before failure. My thinking on this is that (in my simplified model) the gear fails by shearing off a tooth The shear force would be higher on the smaller of two meshing gears so I should only have to look at the cross section of a tooth and the radius of the smaller gear. If I'm correct so far, I'm stuck at the practical means of computing this. Also I have no clue about the strength of PLA and how much shear force it can take.

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  • albertson.chris commented on tanner_tech's instructable Custom Tube Guitar Amp2 years ago
    Custom Tube Guitar Amp

    Who designed the power supply? Please do NOT build this the wiring is just plain wrong and there is no isolation of the AC mains. If you want a safe and same schematic google for "Fender Champ scematic" and see the real thing.Technically what is wrong here is that any decent power transformer will have a primary and secondary that are well insulated from each other. Modern ones even wind the cold on separate bobbins. This way even after a fault the AC mains are galvanically isolated from the DC power. This matters a LOT if you are hiding the metal guitar strings in your hands. People have been killed by designed like is posted here. Please, copy a real schematic, google will find them for you. Using the CD case for a chassis works find, cake pans work too, old am...

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    Who designed the power supply? Please do NOT build this the wiring is just plain wrong and there is no isolation of the AC mains. If you want a safe and same schematic google for "Fender Champ scematic" and see the real thing.Technically what is wrong here is that any decent power transformer will have a primary and secondary that are well insulated from each other. Modern ones even wind the cold on separate bobbins. This way even after a fault the AC mains are galvanically isolated from the DC power. This matters a LOT if you are hiding the metal guitar strings in your hands. People have been killed by designed like is posted here. Please, copy a real schematic, google will find them for you. Using the CD case for a chassis works find, cake pans work too, old ammo boxes or whatever. Just get a real transformer and wire it correctly. The voltage can kill you.

    Yes you like the look but it is totally unsafe. Inside that thin layer of glass is a lethal voltage that can kill you. Every reputable guitar amp makers on Earth places some kind of protection between you and those tubes. Yes I know "I'll be carful" But what about your 5 year old kid and the dog. Exposed tubes are fin for a lab bench experiment but not a working amp you move around and use.Then there is that serious ill-design power supply that is not isolated from AC mains.Fender and marshal placed their chassis in a wooden box so the box offers some degree of safety.

    Not only is it hard to read, it is just plain WRONG and would never be allowed by any safety standard. If you want one that is drawn right look at the Fender web site and download a user/repair manual for a Fender Champ. They use reasonably designed power supplies and professionally down schematics and have the been making them correctly for 50+ years

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