Breakout board based on the integrated 555 (SMD version), one of the integrated circuits that made the history of solid-state electronics.
The 555 is a timer that can be configured in various ways incorporating a pair of comparators whose outputs are connected to the SET and RESET inputs of an RS flip-flop, so as to create astable and monostable, or bistable, multivibrators. But that's not all: the possibility of translating the reference voltage of the pair of comparators, and therefore the voltage at which switching takes place, allows the variable frequency signals to be generated by the NE555, by implementing a real modulator of frequency (FSK) with very few external components and with a minimum space occupation on the printed circuit board.

The breakout board has 4 jumpers to choose four different times (t1, t2, t3, t4), two connectors for power supply and the output connections and trigger input, a row of pitches with pitch 2.54 mm that allow mounting a male pin strip to engage the card on existing hardware.
The power connector is the one that carries 5V, GND and IN (the TTL input of triggers in monostable mode) while the other, besides repeating the 5V transports the outputs, which are that of the 555 (OT) and the collector of the transistor T2 which realizes the power output (OC). On the pin strip, we find instead of all the contacts of the two connectors. Dimensions (mm): 35x22. The kit includes the Breakout board and the two 3-wire cables, 1.25 mm pitch.

• Monostable mode times (see also the following table):

1. - t1: 0.003 s - 3.5 s
2. - t2: 0.01 s - 11 s
3. - t3: 0.03 s - 36 s
4. - t4: 0.11 s - 110 s

• Auctionable mode times: refer to the following table.
• The letter "C" in the table is the value of the capacitor mounted on the PCB.
• TA is the time when the signal remains high, while TB is low.