Audible Logic Probe

When testing circuits with a logic probe, it is sometimes difficult to watch the LEDS on the probe to determine the logic state. With this probe the logic states are audible. This probe is designed for TTL circuits only but could be modified for CMOS. The way it works is as follows. The 5 volt power source will be the circuit under test. Clip the ground input of the probe to the ground of the circuit being tested. The other input lead is used to probe the different chips of the circuit being tested. Any input greater then 2 volts will be high and output a high tone through the speaker. Any input less then .8 volts will be low and produce a low tone through the speaker.

From :: http://home.maine.rr.com/randylinscott/feb99.htm

Logic probe by IC 4050
When you learn digital circuit necessary tool for check logic of the digital. May flee don't pass Logic probe for extremely amateur type our electronics emphasize economize keep before. ...
Logic Probe by 74LS47
This circuit is a Logic Probe. It indicates the logic state of the node of any TTL logic circuit. To do that, we have to supply the probe with the same power of the circuit that we want to ana ...
One-Shot by IC 74LS02
This is circuit Digital One-Shot, use IC TTL Digital 74LS02 : QUAD 2-INPUT NOR GATE . Time Output = 0.8xRxC Related Links More digital circuit More digital circuit More one shot Mor ...
Simple Logic Probe
This simple logic probe has both LEDs on with no signal at the input but due to the nor gates connected to the probe, indicates correctly when a high or low signal is present. It also works co ...
Mini Logic probe with transistor circuit
This is a Logic probe circuit is one,That is suitable for checking the voltage levels in the TTL circuit. It receives from the circuit being tested.Shows how high or low logic level one. The ...