Multimeter - Revision history

Adamcolton at 14:50, 21 June 2019

2019-06-21T14:50:36Z

← Older revision		Revision as of 14:50, 21 June 2019
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	This could also have 5V out (I'll need that for the circuit anyway) and some signal generators (just use the PWM on the AVR).		This could also have 5V out (I'll need that for the circuit anyway) and some signal generators (just use the PWM on the AVR).

			https://hackaday.com/2019/06/20/finally-an-open-source-multimeter/

	== Resistance ==		== Resistance ==

Adamcolton at 15:15, 23 August 2018

2018-08-23T15:15:21Z

← Older revision		Revision as of 15:15, 23 August 2018
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	Could be a good DIY project. Use an AVR~~. My multi-meter doesn't seem to measure capacitance very accurately and I don't like that it's powered by~~ a ~~9V battery~~.		Could be a good DIY project. Use an AVR or a RasPi.

	Features		Features
Line 23:		Line 23:

	[[Category:Electronics]]		[[Category:Electronics]]
	~~[[Category:Projects]]~~

Adamcolton: /* Voltage */

2015-05-30T22:28:06Z

Voltage

← Older revision		Revision as of 22:28, 30 May 2015
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	I want to be able to measure a wide range of voltage at high precision. Say 0-1000V, without frying the AVR. The AVR has a resolution of 4.88mV		I want to be able to measure a wide range of voltage at high precision. Say 0-1000V, without frying the AVR. The AVR has a resolution of 4.88mV

	I should ~~be able~~ to ~~accomplish~~ the ~~primary portion~~ of the ~~circuit with~~ a ~~power~~ transistor. ~~Set it up~~ to ~~limit~~ the voltage ~~drop across a resistor to 1 V~~.		I can do this with 2 pins, 1 transistor, 1 resistor and 2 caps. One pin is PWM out with a shunt cap to average the voltage. This leads to a transistor. The other pin, operating as analog-to-digital converter (adc), is connected to the base, which goes through a resistor to ground. V-in has a shunt cap to ground. The V-in shunt (math needed) should prevent the voltage to the adc from rising fast enough to fry the chip. We use the input from the adc to set the duty cycle of the pwm, trying to keep the adc around 1V, if R is large (like 10kOhm) that should lower the current to a trickle (need to check transistor rating).

			This configuration should lets us get a precise reading (especially if we average over several cycles), leveraging the pwm to adjust the resolution (we can measure increments of a few mV when the voltage is low, but can read large voltage as well, with less accuracy). We can also keep the current draw very low, near the minimum requirement of the transistor.

	[[Category:Electronics]]		[[Category:Electronics]]
	[[Category:Projects]]		[[Category:Projects]]

Adamcolton at 02:39, 30 May 2015

2015-05-30T02:39:16Z

← Older revision		Revision as of 02:39, 30 May 2015
Line 11:		Line 11:

	This could also have 5V out (I'll need that for the circuit anyway) and some signal generators (just use the PWM on the AVR).		This could also have 5V out (I'll need that for the circuit anyway) and some signal generators (just use the PWM on the AVR).

			== Resistance ==
			This should be easiest because we don't have to worry about frying anything. We put 5V across a voltage divider where one resistor is what we want to measure and the other is known. Measure the voltage in the middle, a bit of math, and get the resistance.

			== Voltage ==
			I want to be able to measure a wide range of voltage at high precision. Say 0-1000V, without frying the AVR. The AVR has a resolution of 4.88mV

			I should be able to accomplish the primary portion of the circuit with a power transistor. Set it up to limit the voltage drop across a resistor to 1 V.

	[[Category:Electronics]]		[[Category:Electronics]]
	[[Category:Projects]]		[[Category:Projects]]

Adamcolton at 16:56, 29 May 2015

2015-05-29T16:56:25Z

← Older revision		Revision as of 16:56, 29 May 2015
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	Could be a good DIY project. Use an AVR.		Could be a good DIY project. Use an AVR. My multi-meter doesn't seem to measure capacitance very accurately and I don't like that it's powered by a 9V battery.

	Features		Features
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	* Inductance		* Inductance
	* Transistor measurements (this would be nice if it could identify type, leads and rating)		* Transistor measurements (this would be nice if it could identify type, leads and rating)

			This could also have 5V out (I'll need that for the circuit anyway) and some signal generators (just use the PWM on the AVR).

			[[Category:Electronics]]
			[[Category:Projects]]

Adamcolton: Created page with "Could be a good DIY project. Use an AVR. Features * Resistance * Voltage (AC/DC) * Current * Frequency * Capacitance * Inductance * Transistor measurements (this would be nic..."

2015-05-29T16:54:09Z

Created page with "Could be a good DIY project. Use an AVR. Features * Resistance * Voltage (AC/DC) * Current * Frequency * Capacitance * Inductance * Transistor measurements (this would be nic..."

New page

Could be a good DIY project. Use an AVR.

Features
* Resistance
* Voltage (AC/DC)
* Current
* Frequency
* Capacitance
* Inductance
* Transistor measurements (this would be nice if it could identify type, leads and rating)