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Re: Trouble with a Transducer - Trying to switch it off

 by Valen ¦  Fri Aug 31, 2018 8:45 am ¦  Forum: Projects ¦  Topic: Trouble with a Transducer - Trying to switch it off ¦  Replies: 10 ¦  Views: 784

Yeah, never trust the order of transistor (bipolar or mosfet) pins. It's not a standard. Always consult the datasheet and make sure it is clear in the schematic and pcb layout.

Re: Arduino Thermostat Multiple Outputs

 by Valen ¦  Thu Aug 30, 2018 1:49 pm ¦  Forum: Arduino ¦  Topic: Arduino Thermostat Multiple Outputs ¦  Replies: 6 ¦  Views: 350

I am sorry, I cannot give such suggestions what to buy/replace it with. I have an extremely general mental picture of what your fryer/grill entails as far a hardware goes. I've never done such a project of my own. And I live in another country so advice might not be appropriate for your's. I suggest...

Re: How to power 4.5V LED ribbon with 3V micro:bit?

 by Valen ¦  Thu Aug 30, 2018 5:20 am ¦  Forum: SparkFun Product Questions ¦  Topic: How to power 4.5V LED ribbon with 3V micro:bit? ¦  Replies: 10 ¦  Views: 312

Less length means less current. So that initial transistor would be good after all. About 75 mA per foot

Re: How to power 4.5V LED ribbon with 3V micro:bit?

 by Valen ¦  Thu Aug 30, 2018 4:51 am ¦  Forum: SparkFun Product Questions ¦  Topic: How to power 4.5V LED ribbon with 3V micro:bit? ¦  Replies: 10 ¦  Views: 312

Your suggested transistor seems a bit on the weak side (for a full meter of ribbon) with 200 mA absolute maximum collector current. (Beyond that it may be destroyed) Instead I'd opt for the 4 times stronger BC337: https://www.sparkfun.com/products/13689 Make sure you check the emitter, base and coll...

Re: Arduino Thermostat Multiple Outputs

 by Valen ¦  Thu Aug 30, 2018 4:07 am ¦  Forum: Arduino ¦  Topic: Arduino Thermostat Multiple Outputs ¦  Replies: 6 ¦  Views: 350

I guess it depends on how many pins each LCD screen requires to interface. And how the temperature probes are measured, meaning by the Arduino itself (analog pins) or each probe has a dedicated measurement converter with digital output. And how many pins are required for that to work. If they work w...

Re: Precision Current Sensing Using Arduino

 by Valen ¦  Wed Aug 29, 2018 2:48 pm ¦  Forum: Arduino ¦  Topic: Precision Current Sensing Using Arduino ¦  Replies: 1 ¦  Views: 201

I suggest you lookup Dave Jone's (eevblog.com) µCurrent (microcurrent or ucurrent) current to voltage converter. https://www.eevblog.com/projects/ucurrent/ He went in to much detail in his writing and youtube videos about how it works and the considerations he made during the design of it (in regard...

Re: How to power 4.5V LED ribbon with 3V micro:bit?

 by Valen ¦  Wed Aug 29, 2018 2:14 pm ¦  Forum: SparkFun Product Questions ¦  Topic: How to power 4.5V LED ribbon with 3V micro:bit? ¦  Replies: 10 ¦  Views: 312

Dedicated battery is fine. However coin cells usually do not have that much capacity. They will be drained quickly. Also rather high internal resistance resulting at lower than 3 volt per cell when it has to deliver such current. Your mileage may vary. 4x AAA should work though. Also to power the Mi...

Re: Arduino Thermostat Multiple Outputs

 by Valen ¦  Wed Aug 29, 2018 1:58 pm ¦  Forum: Arduino ¦  Topic: Arduino Thermostat Multiple Outputs ¦  Replies: 6 ¦  Views: 350

Are the appliances (sensor location and heating actuator) located close to one another or are they physically far apart? What temperature probes? Which LCD? 5x LCD to one Arduino (microcontroller)? Why multiple? Can't you operate all from one spot? p.s. It's your job to define the "5x whatever else"...

Re: Reanimating Dead Tissue

 by Valen ¦  Wed Aug 29, 2018 11:58 am ¦  Forum: Projects ¦  Topic: Reanimating Dead Tissue ¦  Replies: 3 ¦  Views: 253

I have an older TENS unit and need a battery. Std. battery is a BL-4C 720mah 3.7vdc LI-ion rechargeable. The batt leads are soldered into the unit's board. It is a very small battery. I cannot find a direct replacement.... Googled for "BL-4C Ebay" and got a cell-phone battery as a first hit. Are yo...

Re: How to power 4.5V LED ribbon with 3V micro:bit?

 by Valen ¦  Wed Aug 29, 2018 11:32 am ¦  Forum: SparkFun Product Questions ¦  Topic: How to power 4.5V LED ribbon with 3V micro:bit? ¦  Replies: 10 ¦  Views: 312

It is questionably if the 3.3 volt regulator on the micro-bit can supply the 250mA per meter. In any case if it lights them up it will be very dim. Seemingly turned off. Since the micro:bit is supplied through a micro-USB cable socket there should be 5 volt on it somewhere. However I am too unfamili...

Re: noob -help

 by Valen ¦  Mon Aug 27, 2018 6:36 am ¦  Forum: Projects ¦  Topic: noob -help ¦  Replies: 1 ¦  Views: 341

A generic led requires at most 20mA. As they drop 1.8 to 2 volts they use 40mW each. Let's start at the beginning. What are the specs of those 5mm LED bulbs. Do they only need to light up when there is sunlight? Or must it use a stored power source. Do you really need 6 Watt panels? Or is that just ...

Re: Supplying Arduino Pro Mini 3.3V

 by Valen ¦  Mon Aug 27, 2018 6:22 am ¦  Forum: Arduino ¦  Topic: Supplying Arduino Pro Mini 3.3V ¦  Replies: 5 ¦  Views: 327

Both! Each has it's pro's and con's! A lipo weighs less for the same capaciy. But requires more accurate circuitry to prevent crossing undervoltage (discharge) and over-charge (voltage) limits. Lipo's can catastrophically fail if abused (fire!). SLA is more robust. SLA is heavier, but more lenient w...

Re: IR Emitter/Detectors for 12 feet distance Halloween project

 by Valen ¦  Mon Aug 27, 2018 6:03 am ¦  Forum: Forum ¦  Topic: IR Emitter/Detectors for 12 feet distance Halloween project ¦  Replies: 3 ¦  Views: 1758

This type of IR detectors usually works better in stray IR light.. When lighting it up with pulsed IR light it is better able to ignore ambient conditions. It outputs a low signal if it detects IR pulses at 38 kHz. : https://www.sparkfun.com/products/10266 At the same time you might want to use a pr...

Re: Supplying Arduino Pro Mini 3.3V

 by Valen ¦  Mon Aug 27, 2018 5:42 am ¦  Forum: Arduino ¦  Topic: Supplying Arduino Pro Mini 3.3V ¦  Replies: 5 ¦  Views: 327

That entirely depends on the capacity of the battery, quoted in units of mAh(ours). A huge 3.7v lipo might last longer than a small 6 volt SLA battery. The internal voltage regulator burns away the excess voltage above 3.3 volt. Current use is the same. If you really want to improve the voltage regu...

Re: AD8232 ECG Board shows square waves

 by Valen ¦  Sun Aug 05, 2018 3:18 am ¦  Forum: SparkFun Product Questions ¦  Topic: AD8232 ECG Board shows square waves ¦  Replies: 6 ¦  Views: 376

Does it work better if you power it through USB instead of that power plug?

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