Ramsey Electronics manual Construction of the URC1

CONSTRUCTION OF THE URC1:

The first thing we will do with this kit is check all of our parts and pieces to make sure we have them all. Use the parts list and your layout diagram to do this. If there are any differences, make sure the schematic agrees with what you have, and also be aware of the tolerances parts have in a kit. Non-critical parts can vary quite a bit with almost no effect on kit operation. For example you may get 1uF capacitors in place of 10uF capacitors, or a 3.579 crystal in place of a 3.579545 crystal. No harm done as these will make no difference in kit operation. Note there are two boards in this kit, as we will start with the larger main board in our assembly. You may have to break apart the two boards depending on how they are shipped.

ˆ1. Orient the circuit board as shown in the parts layout diagram.

ˆ2. Install J1, the PC mounted 1/8" minijack. This is where you hook up the audio with the DTMF tones.

ˆ3. Install C14, a 47uF electrolytic capacitor. Electrolytic capacitors are polarized and must be installed correctly. They are usually marked with a black stripe and a ( - ) indicating their negative lead, while PC boards will usually indicate the ( + ) hole.

At this point you may wish to make the decision of whether or not to use IC sockets to mount your ICs. Though they will add to the cost of your kit, they will prevent the horror of soldering in ICs the wrong direction, or the inability to easily replace a bad IC yourself. If you are a confident good kit builder, you wont have to worry about this.

ˆ4. Install U7, the 4 channel digital to analog converter (MAX 500, 16 dip). Pay extra close attention to the orientation of this device and make sure it is installed in the same direction as in the parts layout diagram. Notice the part has a tab or dimple representing pin 1. Also note that most if not all of these components are static sensitive so if you want to be cautious, ground your body with a clip lead to a ground such as an oscilloscope chassis. Make sure and practice good soldering skills, and keep an eye out for solder bridges or cold joints as you go.

ˆ5. Install C6, a 10uF electrolytic capacitor. Make sure and check polarity before soldering!

ˆ6. Install R4, a 47K resistor (yellow-violet-orange).

ˆ7. Install the 20 pin IC socket where U6 is to go, the microcontroller IC with the sticker marked URC1. Gently insert the U6 into the socket noting where pin 1 is. Pay close attention to the orientation of the tab on this part.

URC1 • 8