12

A relay is almost certainly NOT the right tool for the job. The first step in wiretapping an interface in order reverse-engineer it is to determine the nature of the signals you want to look at. For voltage signals, you need a high-impedance buffer amplifier (like the input of an oscilloscope) that will cause minimal disruption to the existing circuit. For ...


3

The two diodes (D2 & D3) work to OR the voltages, the idea being your 12V_IN will be slightly higher than 12V_BATTERY, so current will flow from 12V_IN to power the device when its present... Minus a diode drop. When 12V_IN is removed current will flow from 12V_BATTERY through D3 R1 is probably there to act as a current limiting resistor for charging ...


2

First of all, my time measuring was faulty. I've noticed that during data sampling intervals systemcalls do not increase my measured overall time, wallclock time was much higher. After raising i2c port speed from 100khz to 400hz i was able to get 4 times as much samples. So i assume,that I've encountered i2c bottleneck


2

The problem is probably interference between the power supply and the telephone line. Telephone lines and power lines should be isolated from one another, but cheap devices (the DTMF decoder, or the power supply, or both) may skimp on isolation - if it were a circuit with a speaker, you would hear a loud humming noise. This goes along with the USB ...


1

This answer does not attempt to address your real question but is only to clarify your understanding. This is my problem, I bought this circuit to receive caller ID over protocol DTMF. As JRE has pointed out, you are confusing DTMF (dual-tone, multi-frequency) with Caller ID. Figure 1. DTMF frequency matrix. Pressing any button transmits the row and ...


1

This diagram is incomplete as it is missing bypass capacitors. Typically they would be 100 nF to 10 uF. The 1K resistor limits charge current to just 12 mA max, much less if battery is close to full charge. This would be an unregulated 'trickle' charger. The diodes are used for reverse polarity protection.


1

According to the datasheet, the SN74AHCT138N is not qualified for output currents greater than 8 mA. If your LEDs truly are 5 V devices (in that they have current limiting built-in), what is their typical operating current at 5 V? As the CMOS output current demand increases, the output voltage rises above GND, decreasing the voltage across the LED. As ...


1

You haven't got any of your enable pins connected. You should have pull downs on your inputs.


1

If you search the Web for this issue you will find LOTS of people that have tried everything to get rid of the "under voltage" indicator. The problem seems to often be the power supply or the cable being used. In your case it sounds like you have tried everything! This is not a fix of your problem, but it is a way to get rid of the under voltage warning. ...


1

With only a voltage regulator on the the output of the solar cell, the efficiency will be low. Use an MPPT tracker module before the voltage regulator to mach the solar panel output with the load. The MPPT tracker is not essential but will allow you to use power from the solar cell in a wider variety of lighting conditions, and at higher deficiencies. In ...


1

In case this is correct which is the battery life in hours? Your battery has MAX 63WH, your load is 7.5WH, so roughly 7.5 hours max runtime. You also have to factor-in efficiency losses, 10~15% and LiPo cycle health. LiPo battery life cycle drops significantly when discharging them all the way down to 0% capacity. It's better to leave at least 30% in them, ...


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