Circuit Editing

At the bottom of the screen are several circuit symbols. In Log lingo, these are called gates. The area above the blue lines is the drawing area, where you draw your circuit diagrams. When you start Analog, two very special gates, the the clock icon and the Analog scoreboard, show up automatically. You are welcome to move these around or delete them if you like, but you will find them extremely handy to have nearby. (If you are using Log as a digital simulator these gates will not appear.)

To begin drawing a circuit, choose the circuit symbol you want, press down on it and drag it (still holding down) to the desired place. To move a gate, just press and drag. To delete a single gate, just "throw it away" by moving it to the bottom corners of the screen.

If you don't see the gate you want in the menus, tap the word CAT to see the "gate catalog." You can then press and drag any of these gates to add it to your circuit. If you will be using a lot of a particular kind of gate, you can drop it into one of the several menu slots to replace another less interesting gate. If you get into the catalog by accident, press an empty part of the screen, or, as usual, hit Control-C to get out.

More about gates

If you look closely at a gate that has been put into the drawing area, you will see some red dots. These are called the gate's red dots, or pins, and they are the places to connect other circuit elements. The easiest way to connect two gates together is to put them down with the appropriate red dots on top of each other.

The single most common mistake in Log is to stick two gates, e.g. a capacitor and a ground, so close together that they look connected but their red dots pass through each other. The gates are NOT connected, and the circuit will NOT simulate correctly. The solution is to nudge the gates apart a bit, then refresh the screen (space bar) to make sure the red dots are aligned.

If the gate comes in an awkward orientation, you can tap it to rotate it by 90 degrees. This works for gates in the circuit as well as for menu-area gates. Notice that Log distinguishes between tapping a gate, to rotate it, and pressing a gate, to move it. Practice a few times until you can tap and press at will, without getting confused. (Some gates, like switches, do special things when you tap them in the circuit. These can only be rotated in the menu area.)


A much neater way to connect things is with wires. To draw a wire, just tap the place you want to start, move horizontally or vertically, then tap the endpoint. This automatically starts a new wire at the endpoint, so you can make a chain of connected wires. To finish the chain, just tap the right mouse button. The whole sequence of tap-tap-rest takes a few minutes to learn but soon feels very natural.

You can move wires by pressing and dragging, just like gates. If you press in the middle of the wire, you move it from side to side but keep the same length. If you press one of the ends, you also get to stretch that end. As usual, to delete a wire just grab it and drag to the edge of the screen.

Wires are connective along their whole lengths, so you can be sloppy about connecting to gates as long as you at least overlap the red dot. Wires and gates are drawn in slightly different colors so you can tell them apart if you need to.

If you connect wires in a "T", Log "solders" them automatically. If you cross them in a +, Log assumes they are unconnected, so you must go back and tap the intersection to solder them. Because of this, "T"-connections are preferable.

To break a long wire, use the Delete function to cut a small wire segment from the wire.

Moving around schematics

If you should run out of room on the screen for your circuit, you have several options: press < or > to "zoom" in or out on the circuit (these are also available in the Frills menu), or use the arrow keys to "scroll" up, down, left, or right. The drawing area is essentially infinitely large; so large, in fact, that you can get lost due to excessive scrolling. If this happens, Home in the Cursor menu will take you back to the center of the drawing universe.

Log can keep up to 9 circuit diagram "pages" in memory at a time. Each page is associated with a different file. To switch to a new page, press one of the digit keys 1 through 9. Depending on your keyboard, the numbers on the numeric keypad may or may not function in this fashion; however, the numbers on the main keyboard always will.

john [dot] lazzaro [at] gmail [dot] com