4-in-1 Analog Calculator

Justin Roeder — Tue, 09 Jul 2024 19:08:58 +0000

Here are ways to do addition, subtraction, multiply and divide using a multimeter.

Addition

Addition is very simple! To do it just connect some pots in series. With series resistors their resistance adds up.

Subtraction

NOTE: If there are 3 or more pots in series, just set them all the way down to 0 ohms.

Multiply

Again if there are any unused pots set them to 0

Divide

In this animated circuit shows you how the resistors divide the voltage. The resistance isn’t important. You probably want nothing lower than 2.2k(for 32.5v, which is probably the max my adjustable voltage source will give you.) To figure out the current rating use this equation $$I_{max}=\frac{V_{in}}{R}$$ To use that circuit first measure the voltage source output(The numerator of the fraction). Then tap into the resistor chain(the denominator of the fraction). The voltage output from the resistor chain will be the Quotient. You can use any number of fixed resistors and any reasonable value as long is impedance doesn’t go too high where the current is too weak for your meter to pickup. You also don’t want to go too low where your batteries leak or explode or even the resistors could catch on fire if the wattage goes over the rated resistor wattage.

The adjustable voltage source

Here it is. This will give the numerator any number between 1.25 to 32.5. I plan on powering it from 4x 9v batteries. This will provide 36vdc of power. You can use anything from 40v or less. If anything higher is needed you can build a rectifier diode chain, I’m not sure if it’s accuracy is any good. Any adjustable linear voltage regulator is good for this purpose To change the voltage range on the LM317 click here.

The post 4-in-1 Analog Calculator first appeared on Delphijustin industries.

0-30v/0-60v dual power supply

Justin Roeder — Mon, 03 Apr 2023 16:48:35 +0000

Here’s a type of powersupply you should have. It’s good if you’re dealing with OP amps. I took the circuit from eleccircuit.com and modified it to incorporate 2x printer power supplies instead of an AC transformer. It provides a ground that are both positive and negative. LM317 and LM337 regulators are utilized in this circuit. They are the main components of the circuit. It uses 2 diodes and a 2.2k 2W resistor for each regulator’s adjustment to 0v. It has 3 diodes for each regulator to be used as its protection diodes like capacitors and short circuits. The two 5K potiometers adjust the output voltage at each output. Printer power supplies are perfect for this project since their voltages are not too high or low.

The project is built on a dick Tracy lunch box. With the printer power supplies inside with a c7 power cord splitter. It uses LM317 and LM337 to provide both positive and negative voltages. Here’s a joke: So I guess that means the LM317 and the LM337 are like the yin and yang of electronics!

The post 0-30v/0-60v dual power supply first appeared on Delphijustin industries.