This project came about because of a need to accurately calibrate the piles of HP test equipment I have been buying off ebay. This project uses a 10mhz voltage tuned crystal oscillator whose frequency is locked to the GPS positioning system clock. The GPS I used was a Canadian Marconi (CMC) Superstar single board OEM GPS receiver with a Motorola external amplified GPS antenna. The ovenized crystal oscillator is a modified Anritsu MH4100A standard crystal oscillator. [via]
GPS Locked 10Mhz Frequency Reference - [Link]
An AVR controller can be used as a counter, although it is a bit more involved than with a PIC. The reason is that a PIC (at least the 16F84) has an asynchronous counter input. This input will handle frequencies up to app. 40 MHz. AVR’s have a synchronous counter input which is sampled with the clock frequency, so it cannot measure frequencies over half the clock frequency. So, when using a 4 MHz clock, input frequencies must be lower than 2 MHz. Use 40% of the clock frequency to be on the safe side. [via]
A 2.5 GHz frequency counter - [Link]
This basically the frequency meter section of the frequency meter/pulse generator based on the AT90S2313 described elsewhere on this site, combined with the 100 MHz RF interface described in the page about the RS-232 to 100 MHz RF desktop channel adapter. Built and align this is the same manner as the 100 MHz RF desktop channel adapter. The frequency meter has a maximum input frequency of 4 Mhz and counts up to 65535. Time bases of 10 ms, 100 ms, 1 second, 10 seconds, and 100 seconds are selectable from the keyboard via the RF link. [via]
Frequency Meter with 100 MHz RF desktop channel - [Link]
A new bunch of Cornell University student projects 2008 have shown up. One of the projects is a device that is capable to measure various AC power parameters in real time. These include:
- Real power
- Apparent power
- Power factor
- RMS Voltage
- RMS Current
- Energy usage (Kilowatt-Hours)
Frequency counters are very popular and easy to build projects. This one is a AT90S8515 microcontroller and Lattice ispLSI2032 PLD based frequency counter. While microcontroller mainly takes care of communicating and data display, PLD counts incoming pulses and scales them down because of hardware 36bit counter implemented. When counter counts up – it generates an interrupt for MCU.
Frequency counter also has ability to communicate with PC via serial port. This way counter can log data to computer or be simply controlled by computer. Project files and source codes are available for download in project page. [via]
Universal frequency counter - [Link]
Jesper writes: This is another project which fullfills a need. I once built a frequency counter using plain TTL chips. That was long before the CMOS HC versions, even before LS was available. It could measure up to 50 MHz and worked quite okay, but the TTL chips was extremely power hungry. I think there was about 20-25 TTL chips on that monster. Well, but the old counter is now somewhere in the shed, and as I now again needed a counter, I did a bit more modern design.
It uses only 4 chips – 3 HC TTL’s and an Atmel At90S2313 microcontroller. It has a 5 digit LED display plus one used as a band indicator. Even with the LED display, the current consumption is less than 50 mA. It counts up to at least 52 MHz. I couldn’t find any signal source in the lab that could supply more than 52 MHz, so it may go a bit higher, but the fClock(typ) for the HC590 is about 35-40 MHz, so you shouldn’t really count (no pun intended) on more. [via]
AT90S2313 Based Frequency Counter - [Link]
The counter contains only three inexpensive ICs (well, add a regulator and three transistors), and operates from 6 – 15V DC at about 25mA. The most expensive single item is the LCD display, which is an industry standard 16 x 2 dot matrix module, which can often be found used or at bargain prices. This isn’t a kitset, but the parts are easily obtained, and the circuit can be built using any prototyping technique, or you could design your own PCB. The prototype was built on a small commercial strip board. [via]
AVR Frequency Counter with LCD - [Link]
This is simple MAX038 generator. It produces sine, triangle and square waves from 1Hz up to 22MHz. The Amplitude, offset and duty cycle are adjustable to offer wide range of generated signals.
Frequency adjustment is made as a rotary switch S8 with a capacitor bank and variable resistor P7. Amplitude, offset and duty-cycle are performed via variable resistors. Switch S5 selects generated waveform.
MAX038 generator- [Link]
I just finished building a frequency synthesizer with the MAX038 waveform generator from MAXIM, you can download the datasheet here: MAX038 High-Frequency Waveform Generator. My circuit is a copy of the high frequency waveform generator in the datasheet, with a 16F877 PIC controlling the device.
Below you can see some pictures of my design (click on the picture to enlarge it):The main PCB, with MAX038 high frequency waveform generator, powersupply and 16F877 PIC controlling the frequency synthesizer. I have detected a small error in the PCB, pin 11 and 12 on the MAX038 IC has to be connected to ground.
Frequency synthesizer with MAX038 - [Link]
That’s a really nice LC Meter Based on the AVR Microcontroller. It calculates and displays L and C from oscillation frequency using reference components. No relays, no range switching, a minimum of controls. And it is pretty accurate too! The 2 line x 16 character LCD shows the calculated inductance and the oscillation frequency. The frequency might be of interest because inductors with cores can appear to vary in inductance with changing test conditions.
A Pretty Good LC Meter Based on the AVR Microcontroller - [Link]