diff --git a/day20.py b/day20.py
new file mode 100644
index 0000000..a5c9122
--- /dev/null
+++ b/day20.py
@@ -0,0 +1,151 @@
+from __future__ import annotations
+import math
+from collections import defaultdict, deque
+from tools.aoc import AOCDay
+from typing import Any
+
+
+class Module:
+    def __init__(self, name: str, machine: Machine):
+        self.name = name
+        self.machine = machine
+        self.state = False
+        self.last_input = defaultdict(bool)
+        self.inputs = []
+        self.outputs = []
+
+    def add_output(self, output: str):
+        self.outputs.append(output)
+
+    def add_input(self, input: str):
+        self.inputs.append(input)
+
+    def send(self, signal: bool):
+        self.state = signal
+        for output in self.outputs:
+            self.machine.send(self.name, output, signal)
+
+    def receive(self, sender: str, signal: bool):
+        raise NotImplementedError()
+
+
+class Broadcaster(Module):
+    def receive(self, sender: str, signal: bool):
+        self.send(signal)
+
+
+class FlipFlop(Module):
+    def receive(self, sender: str, signal: bool):
+        if not signal:
+            self.send(not self.state)
+
+
+class Conjunction(Module):
+    def receive(self, sender: str, signal: bool):
+        self.last_input[sender] = signal
+        if sum(self.last_input.values()) == len(self.inputs):
+            self.send(False)
+        else:
+            self.send(True)
+
+
+class Machine:
+    def __init__(self):
+        self.queue = deque()
+        self.send_signals = {
+            True: 0, False: 0
+        }
+        self.modules = {}
+
+    def add_module(self, module: Module):
+        self.modules[module.name] = module
+
+    def update_connections(self):
+        modules = list(self.modules.values())
+        for module in modules:
+            module.inputs = []
+
+        for module in modules:
+            for output in module.outputs:
+                if output not in self.modules:
+                    self.modules[output] = FlipFlop(output, self)
+                self.modules[output].add_input(module.name)
+
+    def send(self, sender: str, destination: str, signal: bool):
+        self.queue.append((sender, destination, signal))
+
+    def push_button(self, monitor: str = None):
+        self.send('button', 'broadcaster', False)
+        monitor_highs = []
+        while self.queue:
+            sender, destination, signal = self.queue.popleft()
+            if destination == monitor and signal:
+                monitor_highs.append(sender)
+            self.send_signals[signal] += 1
+            self.modules[destination].receive(sender, signal)
+
+        return monitor_highs
+
+    def get_signal_value(self) -> int:
+        return self.send_signals[True] * self.send_signals[False]
+
+
+class Day(AOCDay):
+    inputs = [
+        [
+            (32000000, "input20_test"),
+            (11687500, "input20_test2"),
+            (1020211150, "input20"),
+        ],
+        [
+            (238815727638557, "input20"),
+        ]
+    ]
+
+    def parse_input(self) -> Machine:
+        machine = Machine()
+        for line in self.getInput():
+            module_name, targets = line.split(" -> ")
+            if module_name.startswith("broad"):
+                module = Broadcaster(module_name, machine)
+            elif module_name.startswith("%"):
+                module = FlipFlop(module_name[1:], machine)
+            elif module_name.startswith("&"):
+                module = Conjunction(module_name[1:], machine)
+            else:
+                assert False, "unknown module type: %s" % module_name
+
+            for target in targets.split(", "):
+                module.add_output(target)
+
+            machine.add_module(module)
+
+        machine.update_connections()
+        return machine
+
+    def part1(self) -> Any:
+        machine = self.parse_input()
+        for _ in range(1000):
+            machine.push_button()
+        return machine.get_signal_value()
+
+    def part2(self) -> Any:
+        machine = self.parse_input()
+        count = 0
+        input_highs = {}
+        to_monitor = machine.modules["rx"].inputs[0]
+        wait_for = len(machine.modules[to_monitor].inputs)
+        while True:
+            count += 1
+            found_highs = machine.push_button(monitor=to_monitor)
+
+            for high in found_highs:
+                input_highs[high] = count
+
+            if len(input_highs) == wait_for:
+                return math.lcm(*list(input_highs.values()))
+
+
+if __name__ == '__main__':
+    day = Day(2023, 20)
+    day.run(verbose=True)
diff --git a/inputs/input20 b/inputs/input20
new file mode 100644
index 0000000..f0970b5
--- /dev/null
+++ b/inputs/input20
@@ -0,0 +1,58 @@
+%ls -> gl
+%rz -> vm, gl
+broadcaster -> rz, fp, kv, fd
+%ql -> bn
+%bm -> hr, fj
+%fp -> cc, gk
+&lk -> nc
+%xg -> gl, mz
+%dg -> gk, mp
+%zg -> ls, gl
+%lg -> hr
+%pt -> lg, hr
+%sp -> mj
+%ms -> gl, hx
+%kj -> fl, gk
+%bn -> rj, gk
+%xc -> vq
+%fl -> gk
+%dh -> hr, nm
+%jk -> gk, dg
+%tf -> cb
+%kd -> cm, nr
+&hr -> hh, kv, xl, qq
+%kv -> xr, hr
+%hq -> ql
+&fn -> nc
+%vm -> gl, xn
+%jh -> nr, kd
+%mz -> dd
+%tp -> hq
+%cf -> nr
+%gr -> jh
+%jd -> hr, bm
+%xr -> qq, hr
+%cm -> nr, cf
+&fh -> nc
+%rb -> xl, hr
+&nc -> rx
+%mp -> gk, kj
+&nr -> fd, gr, fn, cb, tf, xc, vq
+&gl -> fh, xn, sp, mz, rz, mj, dd
+%rj -> jk
+&hh -> nc
+%fd -> nr, df
+&gk -> lk, tp, fp, ql, hq, rj
+%fj -> pt, hr
+%qq -> dh
+%df -> nr, nv
+%mj -> ms
+%xn -> xg
+%cc -> gk, tp
+%nm -> rb, hr
+%dd -> sp
+%vq -> gr
+%cb -> xc
+%nv -> tf, nr
+%xl -> jd
+%hx -> gl, zg
diff --git a/inputs/input20_test b/inputs/input20_test
new file mode 100644
index 0000000..9ed10dd
--- /dev/null
+++ b/inputs/input20_test
@@ -0,0 +1,5 @@
+broadcaster -> a, b, c
+%a -> b
+%b -> c
+%c -> inv
+&inv -> a
\ No newline at end of file
diff --git a/inputs/input20_test2 b/inputs/input20_test2
new file mode 100644
index 0000000..4da4379
--- /dev/null
+++ b/inputs/input20_test2
@@ -0,0 +1,5 @@
+broadcaster -> a
+%a -> inv, con
+&inv -> b
+%b -> con
+&con -> output
\ No newline at end of file