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HOMEMADE BOARDS
HOMEMADE BOARDS
Some examples of my methods of making circuit boards. You will see I do not care about appearance, just that it works!
These were done when I was in my Softrock construction and modifying days. 2020 these are still working, not unreliable!
Also at the bottom, modifying the Khune heater.
Below is a picture of my board and the tools used to make it. After scoring the board is cleaned with sand paper and the grooves cleaned out. This may be done a few times, looking with an eyeglass until no debris remains. This seems crude but I have used this technique for many years, providing no swarf is left it proves a reliable method. These have been used to convert earlier crystal controlled Softrocks to make them frequency agile. Tony once produced a kit with a proper board to do this.
This page was intended to show how one can get away without a printed circuit. DIL ICs can be mounted upside down (Dead Bug) like the Si570 on similar boards. With the right tools and skills SOICs may be similarly wired.
The board is double sided, the drilled holes are used to connect with the ground plane on the reverse. After the photo I drilled a few more. Size 40 x 23mm, 1 3/4 x 1"
The populated board:- Semiconductors from left side. The Si570 is 5x7mm, small but not too small. A fine tip is needed.
Centre left, FIN1002 level converter. This is a LVDS receiver, it may be mounted away from the Si570, connected with a twisted pair terminated with 100R. Centre Si570. A 100nF capacitor is mounted vertically next to the +ve pad. See lower picture.
Right LP2992 3V3 regulator. Note, for stability under all conditions, a ceramic 4u7 capacitor is recommended for the output of this regulator but I have not used one but a 10uF and 100nF instead.
A 68R in series with the 12V supply reduces the regulator dissipation. At about 100mA the resistor dissipates over 1/2 watt. This point may be supplied with 5V from a suitable regulator.
I have used surface mount components, mainly second-hand removed from old boards! Wired components may, of course be used tacked on like my interconnecting wires.
The Si570 is decoupled by a surface mount 100nF mounted vertically.
2 FETs to interface with the LPT parallel port, for frequency control. For PicAxe etc I2C control connections made direct to SDA, SCL. (PicAxe runs off the 3V3 line.)
More convenient now would be a USB ATTiny85 as in the Softrock. Or an independent controller as lower on this page.
Another attempt for another Si570. This time I have terminated the LVDS input to the FIN1002 although this may not be necessary for such a short twisted pair.
This board was made for the WA6UFQ Si570 controller. It takes a few hours to design and make. If size is critical, and you know exactly what components will be fitted then place them on the board and draw the tracks in pencil. Like other boards I have drilled a few holes to link to the ground plane on the other side. This is built only for the Si570, I have omitted the components required to interface with the DDS 30/60 which it also will control.
The populated board. On the other side is the PIC, a resistor array and the 10MHz crystal. Also two sockets to take the LCD leads. I then removed the sockets to reduce the height of the board and wired an LCD directly. The red lead is the5V connector for the LCD power. This is taken from the 5V regulator in the Si570 box. (It is actually outside, to minimise the heat inside.) Care should be taken if you use this for the LCD backlight, it may need a bigger heatsink. The connector goes to the Si570, on the Softrock 6.3 & 8.3 it may go to the PIC socket. It connects the SDA, SCL, 3V3 & ground.
The board and mouse wheels were cut and fitted into a box made with more double sided board. (Facia to follow, perhaps!) The mouse wheels are a little fiddly to use but do the job. The switch of one is used as the "set" switch. Their connections found by just trying each of the three pins to ground in turn until they worked properly. Note they work after a fashion whichever way they are connected! The controller is attached to a stand-alone Si570 unit. This has a PIC controller stuck on it which plugs in to the unit. there is also a connector for paralell port control.
A Kees, K5BCQ/John controller I built. And some notes about rotary encoders.
Here is a really good way of using PCB material for circuits and boxes. Now on http://aa7ee.wordpress.com/ Look for August 2nd and September 24 2011. June 2018, It is still there, you have to scroll down and down and down.....
Si570 Temperature Stability. At 5MHz (divided frequency) the frequency has varied 3Hz over a week when the room has varied 5 degrees Centigrade. I have mounted one on a Khune crystal heater and observed a movement of around 1Hz under similar conditions. The Khune heater holds a temperature of 40 Centigrade so would not work well in the tropics.
I have insulated a Si570 with a thermocouple probe in contact with the cover. It measured 46°C varying with exact frequency. I modified the Khune to run at 50°C for better stability.
The Khune ran at 50°C when I shorted the resistor (561 on mine) at bottom right on this picture.
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