Safety

Read this page before you connect WaveLink to anything. The instrument can put ±7.58 V on its output BNC, and its input has no attenuator or clamp of its own, so the safe input voltage is set by your probe and gain setting rather than by the board. Both of those limits have consequences for whatever you attach.

WaveLink is a student-built laboratory instrument. It is not certified test equipment. Do not connect it to mains-referenced circuits, to anything carrying line voltage, or to any circuit outside the input rating given below. There is no reinforced isolation between the input BNC and the rest of the board.

Output limits

Parameter	Value
Maximum amplitude	15.15 Vpp
Minimum amplitude	0.93 Vpp
DC offset range	±7.58 V
Absolute output rail	±10 V (hard clip)

The output stage clips at ±10 V no matter what you request. That is a rail, not a protection feature — a clipped waveform is still a 20 V peak-to-peak signal being driven into your circuit.

Set your amplitude before you connect a load. The amplitude control is a pair of digital potentiometers, and their position persists across power cycles in EEPROM. If the last person to use the board left it at maximum, that is what comes out of the BNC the moment you power up.

After a firmware reflash, the output returns at maximum amplitude. The digital potentiometers have no read-back path, so the firmware homes them at boot and then restores the saved positions from EEPROM. A chip erase -- which the firmware build performs on every flash -- wipes those saved positions, and the wipers come back at position 99, which is 15.15 Vpp. Check and set the amplitude before connecting anything sensitive to a freshly flashed board.

Input limits

There is no input attenuator and no protection clamp on this board. Whatever you connect to the input BNC reaches the programmable gain stage directly. The only attenuation in the system is the probe you attach, and the only protection is relay K4, which merely disconnects the input while the scope is idle -- it does nothing once the scope is running.

The converter node saturates at ±2.5 V, so the safe input depends on both the gain you have selected and the probe you are using:

Chain gain	At the BNC (1× probe)	Through a 10× probe
Minimum (×0.19)	±13.2 V	±132 V
Unity	±2.5 V	±25 V
Maximum (×3.03)	±0.83 V	±8.3 V

Treat the middle column as the instrument's rating. The right-hand column is the probe's doing, and it evaporates the moment a 1× probe or a bare lead is fitted -- a lead that measured a 20 V rail safely at 10× puts the full 20 V into the gain stage at 1×. The ±132 V figure is arithmetic, not a safety rating: it assumes a probe rated for that voltage and says nothing about the board.

If you do not know the amplitude of the signal you are about to measure, start at minimum gain, or use Autoset — it deliberately searches upward from minimum gain so the comparator input is never overdriven on the way.

Fail-safe behaviour is fail-open, not fail-safe

The output mute relays K2 (CH1) and K3 (CH2) mute when energised and pass signal when de-energised. This is worth understanding clearly:

A board that loses power does not mute its outputs. It passes them.
A board whose microcontroller has crashed or reset does not mute its outputs.
The muted state is the state that costs coil current to hold.

In practice this means you should never rely on “the board is off, so the output is safe.” Disconnect the load, or confirm the amplitude, instead.

Before you power on

Confirm nothing is connected to the output BNC, or that whatever is connected tolerates 15.15 Vpp.
Power the board, connect over BLE, and read the current amplitude from the app — the hardware is the source of truth, and the app reads the real wiper positions on connect.
Set the amplitude and offset you actually want.
Only then connect your load.

For the input, the same order applies: choose your gain, connect the probe, then acquire.