Prescaller devide by 10 with IC CMOS 74HCT390

By using IC CMOS 74HCT390 we can make the cheap prescaller.
Datasheet IC can download here.

Figure above is 74HCT390 logic symbol

This Prescaller I have tried and use the Frequency counters that measure the ability for HF Frequency counter (0-30MHz) can also be used to measure the frequency VHF (30-300MHz).
To measure the small signal circuit will be added buffer / pre-amp before the signal is inserted into prescaller.
Design construction can use PCB assembly or perforated with ugly style that all these prescaller circuit can be added to the box Freq counter and switches can be added to the measurement of the input frequency HF or VHF.
Need to be careful in the construction, make sure the connection is especially true in the provision of the CMOS voltage must be stable 5V. I've ruined this IC because there is over-voltage.

Homebrew 30Mhz Frequency Counter

Design tools that I created is based on an amateur radio OM3CPH, the site he was actually there are 2 kind of design are Seven segment display and LCD display. To save money so I select the design that using Seven segment display.
Construction: For Schematic, PCB and PIC source programs I use OM3CPH original design or can download here , for the power supply is very easy to make that could provided a stable 5V voltage to the PIC microcontroller, for box case can be made according to our tastes, of this I use acrilig formed sheet and the box cover use material from PCB sheet. Front panel of the box we can print with our personalizing , printing is made by computer and I stick with double-sided tape.



Peripheral: For the purposes of measurement must have a suitable probe, using probes with a length of cable as needed. To probe Conector ground used for the crocodile and measuring probes use the osiloscope probe but with a cheaper version.
Have Fun...

How to Interface a Microchip PIC MCU with a hobby R/C Servo

Servo motors can be used with success in several different robotic applications. The have a very simple electrical interface and are available in a great assortment of specifications and prices.
Usually one can get started with a very cheap one. This paper will show how to control one of these servos using a PC and a microchip PIC microcontroller. For read more see here.

Making the VFO PLL for High Frequency

Homebrew multiband SSB transceiver part 6

Programmable IC TC 9122 DEVIDER was only able to divide frequency up to approximately 14 MHz at 6-volt voltage.
For the ability devider is 1 to 3999.
Therefore, if the frequency that must be shared exceeds the capacity it should be held down Conversion, which required pre-mixer.
For example the 5266 KHz IF frequency to be work in the 14250 KHz band is required to vfo frequency 14250 + 5266 = 19516 KHz PLL so must be made
who worked around 19516 KHz.

In this project the set Oscilator Reference 1KHz, was
Xtal oscillator taken 16 MHz. Because 16MHz crystal
available lots in the market.

From the block diagram above can be calculated that the frequency of
into the TC 9122 to work on 14250KHz is 19516KHz -16000KHz = 3516KHz. 3516 numbers are still under number 3999 of the divider TC 9122. So the 14250KHz working frequency must be programmed for the TC9122 to 3516 that if written in BCD: 11 0101 0001 0110
Control circuit used for IC CD4029 up / down counter that can be programmed.

To move UP / DOWN is used two IC CD4011 also as debouncer. Encoder dial can
use mechanical systems that available in the market. Dial encoder can be used from the component MOUSE computer unused / damaged.

To make the VFO on the other band, the market can be found in the crystal
with frequency 3, 5, 6, 8, 10 and 16 MHz that can be tried to achieve the desired frequency band

Digital decoder for PLL

In the example of the use of TTL IC this time, we will try to submit a design Switch to set UPDOWN operating frequency of a PLL which uses TC 9122. First we will take the IC 7400 to create two inputs to the flipflop as the following counter is 74192.

Figure 1.Updown digital switch

With the above design, when the UP button is pressed, IC1 will count forward, and the calculation results will be issued as a Binary coded Decimal via pin 3, 2, 6 and 7. If the count at IC1 has reached 10, it will give one IC1 to IC2 pulses that will calculate forward IC2 and IC1 ONE count back to ZERO. BCD output is then used as input to the PLL to adjust the working frequency.

Figure 2.Seven segment display

If the output is sampled and used as input to the IC 7447 to turn 7 segment, the results of this calculation can be displayed.