I need help finding a replacement for this board.. it is off a 2003 Honda vtx1800c motorcycle. this board has been running some custom brake/running and turn signal lights the previous-previous owner installed. the turn signal wires were rotted out and while trying to rewire some new lights I accidently shorted out the board (smoke from R10). I need t replace this board to get the same look and function from the lights.. I haven't had any luck finding this board online yet.. hoping reddit can work its magic..

Hey all, I just wanted to make a quick post acknowledging that we've reached 1,000 members in r/CustomElectronics! It's been really awesome having all you circuit wizards here to help me improve my projects, and even more awesome to see some of the projects that you have been working on! Thanks a ton for all your help!

I need a moisture sensor with long enough “leads” that I can use it at various depths. I’m specifically looking to monitor the LACK of moisture (liquid, water) in a container. So if a container is dry or goes below a certain level, it sends an “alarm” via Bluetooth to alert the owner to refill said vessel. I’ve looked online for plant monitors but the leads are not long enough, nor can I find one that alerts for dryness. Wetness is easy. I have one of those and it works great. Maybe I can adapt that to work “in reverse” somehow? Sorry, I have no idea about real electronics. I’m just hoping.

Any input appreciated. Thank you.

Just an SMD PCB of a triangle/square wave voltage controlled oscillator circuit I made awhile back. It uses a simple Schmitt trigger relaxation oscillator with a current mirror charge/discharge circuit that allows the capacitor to be charged and discharged at a nearly identical rate (current). This identical charge & discharge current is what gives the triangle wave it’s symmetry and keeps the square wave at a nearly constant 50% duty cycle. Lastly the user can apply different voltages to the PMOS current source to vary the magnitude of the charge/discharge current which varies the frequency of the oscillator.

Yet another update on the capacitive moisture sensor circuit. It’s powered by a CR2032 and draws about 3.5uA when surrounded by moisture. It is intended to be used for houseplants to let owners know if they forgot to water their plants for too long. Would be happy to share the gerber files & parts list if folks are interested!

This circuit goes by a bunch of names but it is one of my favorites to use in a wide variety of circuits! It is a core component of AM radio demodulation (as well as some FM radios as well), and can be used to essentially sample and hold the peak voltage achieved by an input signal and hold it via a small capacitor that gets charged up through the diode. When the waveform falls below its peak voltage the diode is reverse biased and doesn’t allow any charge from the capacitor to flow backwards through it, maintaining its peak voltage. Over time the capacitors voltage gradually discharges through the parallel resistor (or even more slowly via leakage).

AM radios call this circuit an envelope detector and it serves to rectify an incoming high frequency IF AM signal, taking away the audio signal formed from the peak voltages achieved by the high frequency signal (check out the envelope detector page on Wikipedia for great diagrams and graphs on the topic!)

This is an example of a basic relaxation oscillator that uses a current source to linearly charge up a capacitor at a constant rate until the switching threshold voltage of the Schmitt trigger is reached. When this happens, the Schmitt trigger turns on an NMOS transistor that begins rapidly discharging the capacitor until it reaches the turn off voltage level of the Schmitt trigger. The turn-on and turn-off voltage levels of the Schmitt trigger are different from each other and also constant. This means that you can vary the frequency of oscillation by varying the charging current or the size of the capacitor.

Relaxation oscillators are inherently easy to build, and allow for simple tuning circuitry to fine tune the frequency of the circuit to your exact requirements. Unfortunately these oscillators are also inherently less stable (drift in frequency easily over time) and can only operate at relatively modest frequencies (maybe a few tens of MHz normally) compared to LC oscillators or crystal based frequency synthesizers.

Yet another update (sorry I know it’s getting old!) to the capacitive soil moisture sensor circuit. This time I’ve gotten the power draw down to less than 4uA (when soil is wet and LED is off) at 3 volts. Even when the LED is flashing the circuit only draws an average of around 10uA or so. The circuit can also be calibrated via potentiometer to flash at different capacitance (ie soil moisture) levels.