diff --git a/package.json b/package.json
index 1813a99..7a4df94 100644
--- a/package.json
+++ b/package.json
@@ -8,7 +8,7 @@
     "build": "tsc -b && vite build",
     "lint": "eslint .",
     "preview": "vite preview",
-    "test": "vitest run src/__tests__/BerlinClock.test.tsx",
+    "test": "vitest run src/__tests__/*",
     "format": "eslint . --fix && prettier --write .",
     "e2e": "cypress run",
     "ci": "npm run format && npm run test && npm run e2e"
diff --git a/src/__tests__/DigitalClock.test.tsx b/src/__tests__/DigitalClock.test.tsx
index 0381d1e..20e53f5 100644
--- a/src/__tests__/DigitalClock.test.tsx
+++ b/src/__tests__/DigitalClock.test.tsx
@@ -1,8 +1,81 @@
-import { render } from '@testing-library/react';
+import { render, screen, fireEvent } from '@testing-library/react';
 import { DigitalClock } from '../containers/DigitalClock';
+import * as utils from '../utils';
+
+vi.mock('../utils');
+
+const mockedDateToDigital = vi.mocked(utils.dateToDigital);
+const mockedDigitalToDate = vi.mocked(utils.digitalToDate);
 
 describe('DigitalClock', () => {
-  it('renders when enabled', () => {
-    render(<DigitalClock enabled={true} />);
+  const onTimeChangeMock = vi.fn();
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+    mockedDateToDigital.mockReturnValue('14:30:15');
+    mockedDigitalToDate.mockImplementation((str: string) => {
+      const parts = str.split(':');
+      if (parts.length !== 3) return new Date(NaN);
+      const [h, m, s] = parts.map(Number);
+      if (isNaN(h) || isNaN(m) || isNaN(s)) return new Date(NaN);
+      const d = new Date(2025, 0, 1, 14, 30, 15);
+      d.setHours(h, m, s, 0);
+      return d;
+    });
+  });
+
+  it('renders nothing when disabled', () => {
+    const { container } = render(
+      <DigitalClock
+        enabled={false}
+        currentTime={new Date(2025,0,1,14,30,15)}
+        onTimeChange={onTimeChangeMock}
+      />,
+    );
+    expect(container.innerHTML).toBe('');
+  });
+
+  it('renders the digital time and input when enabled', () => {
+    render(
+      <DigitalClock
+        enabled={true}
+        currentTime={new Date(2025,0,1,14,30,15)}
+        onTimeChange={onTimeChangeMock}
+      />,
+    );
+    expect(screen.getByTestId('digital-clock')).toHaveTextContent('14:30:15');
+    expect(screen.getByTestId('time-input')).toBeInTheDocument();
+  });
+
+  it('calls onTimeChange when a valid time is entered', () => {
+    render(
+      <DigitalClock
+        enabled={true}
+        currentTime={new Date(2025,0,1,14,30,15)}
+        onTimeChange={onTimeChangeMock}
+      />,
+    );
+    const input = screen.getByTestId('time-input');
+    fireEvent.change(input, { target: { value: '12:00:00' } });
+
+    expect(onTimeChangeMock).toHaveBeenCalledTimes(1);
+    const expectedDate = new Date(2025, 0, 1, 12, 0, 0, 0);
+    expect(onTimeChangeMock).toHaveBeenCalledWith(expectedDate);
+
+    expect(input).toHaveValue('12:00:00');
+  });
+
+  it('does not call onTimeChange when an invalid time is entered', () => {
+    render(
+      <DigitalClock
+        enabled={true}
+        currentTime={new Date(2025,0,1,14,30,15)}
+        onTimeChange={onTimeChangeMock}
+      />,
+    );
+    const input = screen.getByTestId('time-input');
+    fireEvent.change(input, { target: { value: 'notatime' } });
+    expect(onTimeChangeMock).not.toHaveBeenCalled();
+    expect(input).toHaveValue('notatime');
   });
 });
diff --git a/src/__tests__/TimeConverter.test.tsx b/src/__tests__/TimeConverter.test.tsx
index cf4c3de..db0d02b 100644
--- a/src/__tests__/TimeConverter.test.tsx
+++ b/src/__tests__/TimeConverter.test.tsx
@@ -1,13 +1,56 @@
 import { render, screen, fireEvent } from '@testing-library/react';
 import { TimeConverter } from '../containers/TimeConverter';
+import { useCurrentTime } from '../hooks/useCurrentTime';
+
+vi.mock('../hooks/useCurrentTime');
+vi.mock('../containers/BerlinClock', () => ({
+  BerlinClock: ({ enabled }: { enabled: boolean }) => (
+    <div data-testid="berlin-clock">{enabled ? 'enabled' : 'disabled'}</div>
+  ),
+}));
+vi.mock('../containers/DigitalClock', () => ({
+  DigitalClock: ({ enabled, currentTime, onTimeChange }: { enabled: boolean; currentTime: Date; onTimeChange: (d: Date) => void }) => (
+    <div data-testid="digital-clock-wrapper">
+      <span data-testid="digital-clock-time">{currentTime.toISOString()}</span>
+      <button data-testid="set-time" onClick={() => onTimeChange(new Date(2025,0,1,12,0,0))}>
+        Set time
+      </button>
+      {!enabled && <span data-testid="disabled-indicator">disabled</span>}
+    </div>
+  ),
+}));
+
+const mockedUseCurrentTime = vi.mocked(useCurrentTime);
 
 describe('TimeConverter', () => {
-  it('renders the toggle checkbox', () => {
-    render(<TimeConverter />);
-    expect(screen.getByRole('checkbox')).toBeInTheDocument();
+  const setCurrentTimeMock = vi.fn();
+  const baseDate = new Date(2025, 0, 1, 14, 30, 15);
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+    mockedUseCurrentTime.mockReturnValue({
+      currentTime: baseDate,
+      setCurrentTime: setCurrentTimeMock,
+    });
   });
-  it('disables clocks when checkbox is checked', () => {
+
+  it('renders the checkbox, BerlinClock, and DigitalClock', () => {
     render(<TimeConverter />);
-    // TODO
+    expect(screen.getByTestId('use-system-time')).toBeInTheDocument();
+    expect(screen.getByTestId('berlin-clock')).toHaveTextContent('enabled');
+    expect(screen.getByTestId('digital-clock-wrapper')).toBeInTheDocument();
+  });
+
+  it('disables both clocks when checkbox is checked', () => {
+    render(<TimeConverter />);
+    fireEvent.click(screen.getByTestId('use-system-time'));
+    expect(screen.getByTestId('berlin-clock')).toHaveTextContent('disabled');
+    expect(screen.getByTestId('disabled-indicator')).toBeInTheDocument();
+  });
+
+  it('calls setCurrentTime when DigitalClock triggers onTimeChange', () => {
+    render(<TimeConverter />);
+    fireEvent.click(screen.getByTestId('set-time'));
+    expect(setCurrentTimeMock).toHaveBeenCalledWith(new Date(2025, 0, 1, 12, 0, 0));
   });
 });
diff --git a/src/containers/DigitalClock.tsx b/src/containers/DigitalClock.tsx
index 4408719..c97c4d0 100644
--- a/src/containers/DigitalClock.tsx
+++ b/src/containers/DigitalClock.tsx
@@ -1,13 +1,36 @@
 import { useState } from 'react';
-import { useCurrentTime } from '../hooks/useCurrentTime';
-import { dateToDigital } from '../utils';
+import { dateToDigital, digitalToDate } from '../utils';
 
 interface DigitalClockProps {
   enabled: boolean;
+  currentTime: Date;
+  onTimeChange: (time: Date) => void;
 }
 
-export function DigitalClock({ enabled }: DigitalClockProps) {
-  const { currentTime } = useCurrentTime();
-  const digital = dateToDigital(currentTime);
-  return null;
+export function DigitalClock({ enabled, currentTime, onTimeChange }: DigitalClockProps) {
+  const [inputValue, setInputValue] = useState(dateToDigital(currentTime));
+
+  const handleChange = (e: React.ChangeEvent<HTMLInputElement>) => {
+    const value = e.target.value;
+    setInputValue(value);
+    const date = digitalToDate(value);
+    if (!isNaN(date.getTime())) {
+      onTimeChange(date);
+    }
+  };
+
+  if (!enabled) return null;
+
+  return (
+    <div>
+      <span data-testid="digital-clock">{dateToDigital(currentTime)}</span>
+      <input
+        data-testid="time-input"
+        type="text"
+        value={inputValue}
+        onChange={handleChange}
+        placeholder="HH:MM:SS"
+      />
+    </div>
+  );
 }
diff --git a/src/containers/TimeConverter.tsx b/src/containers/TimeConverter.tsx
index 9e35a2e..d536573 100644
--- a/src/containers/TimeConverter.tsx
+++ b/src/containers/TimeConverter.tsx
@@ -4,7 +4,30 @@ import { DigitalClock } from './DigitalClock';
 import { useCurrentTime } from '../hooks/useCurrentTime';
 
 export function TimeConverter() {
+  const { currentTime, setCurrentTime } = useCurrentTime();
   const [useSystemTime, setUseSystemTime] = useState(false);
-  // When useSystemTime is true, both BerlinClock and DigitalClock are disabled.
-  return null;
+
+  const handleTimeChange = (newTime: Date) => {
+    setCurrentTime(newTime);
+  };
+
+  return (
+    <div>
+      <label>
+        <input
+          type="checkbox"
+          data-testid="use-system-time"
+          checked={useSystemTime}
+          onChange={(e) => setUseSystemTime(e.target.checked)}
+        />
+        Use system time
+      </label>
+      <BerlinClock enabled={!useSystemTime} />
+      <DigitalClock
+        enabled={!useSystemTime}
+        currentTime={currentTime}
+        onTimeChange={handleTimeChange}
+      />
+    </div>
+  );
 }