A very handy 10-30V timer for appliances on your boat. The timer can be used to safe-guard appliances like remote electric valves of propane tanks, salt water galley pumps, etc. There are various applications possible. Either build it yourself or buy it from us!
Example usages
Timers can be incredibly handy on a boat. Let's just give two real life examples of usage on ZwerfCat:
Propane valve of the stove
Like many boat owners we have an electrical valve on our propane bottle to minimize risks of explosions. To cook, we just had to flick the switch to "on" to open the remote valve, and when the cooking is finished we have to remember to turn it off again. You see the problem? We (or our guests) often forgot to switch it off, defeating the purpose of the remote electrical valve.
We now use my handy timer: With a quick press on the button the remote valve opens, and after a half an hour the LED of the button starts blinking. A renewed press on the button resets the timer, but if you let it go, 5 minutes later the valve closes automatically. Of course, if you are finished much earlier you can close the valve by pressing the button shortly.
Note: All times are configurable.
Salt water galley pump
We have salt water in the galley for the (first part of the) dishes. On our boat it is just a faucet with a pressure switch controlled salt water pump just like the fresh water system. Problem here is that if ever a hose pops off, the salt water pump will sense the loss of pressure and starts pumping water into the boat, until either the ocean is empty or the power is interrupted, whichever comes first. So, as a precaution, we always switch off the circuit breaker of the salt water pump when we leave the boat, that is, if we don't forget about it.
We now use my incredibly handy timer: With a quick press on the button the salt water pump is enabled, and if we don't need its service anymore we can press the button again to switch it off. If the pump is enabled for more than 30 minutes the LED inside the button starts blinking, we have 5 minutes time to press the button again to reset the timer and keep the pump enabled, or otherwise the power to the salt water pump will be automatically interrupted.
We still make sure that the salt water pump is off when we leave the boat, but at least if we forget about it, in the worst case scenario when the pump was enabled just a minute before we left, and a hose will pop off just a minute after we left, half an hour is all the pump gets in its attempt to sink our boat.
Other ideas
There can be many things on a boat that could be switched off automatically after a certain time:
- Heaters of all kinds
- Inverters
- Fuel polish pumps
- Watermakers
- Pumps of all sorts
- Lights
Usage
Use is very simple: To switch the appliance on, just shortly press the button. The LED inside the button lights up to indicate that the appliance is powered and ready to be used. Just press again to switch it off. If it is on, the timer starts counting and after a (configurable) time the LED inside the button starts blinking. A "renew" press on the button keeps the appliance on, but if nothing is done then after some time (configurable) the appliance will be automatically switched off.
Configuration
The build it yourself version does not have a configuration mode but is programmed by coding the desired settings directly into the software. If you order a ready to be used timer from me, then use the configuration method as outlined below.
The memory of the timer is retained even with the power off. There is no coin cell battery, the configuration is saved into the EEPROM of the timer and will be remembered forever (unless the configuration is changed again).
The appliance will not automatically shut off while in configuration mode.
Configuration of the duration of the timer
To configure the timer, you just operate the appliance manually and the timer will record the duration.
To do this:
- Hold the button for 10 seconds. The appliance switches on like normal, but you see that it is in learning mode because the LED starts flashing rapidly.
- After the amount of time you want it to warn you with a blinking led that the time is almost up, press the button. The LED now starts flashing differently.
- After the amount of time you want the appliance to really switch off, press the button again: the appliance switches off, the timing is now recorded into the memory of the timer.
In case the configuration mode is activated inadvertently (who holds that button for more than 10 seconds inadvertently?) the configuration mode can be cancelled by pressing the button again for more than 10 seconds (if you managed to do that the first time, you can do it again). The existing timing setting will be retained.
PWM configuration
This option is not needed for normal purposes. Don't use it unless you understand its purpose! This option is used to reduce the power going to relays or electric valves, to save power and/or protect them from becoming too hot. If this option is used the output starts with one second of 100% power, then drops off to the configured PWM (Pulse Width Modulation) value, just enough to keep the relay engaged or the electric valve open.
To configure this mode:
- Hold the button for 10 seconds. The appliance switches on like normal, but the LED starts flashing rapidly.
- Press and hold the button for 3 seconds, then release within 2 seconds. The LED pattern will change.
- Press and hold the button; the power will automatically gradually drop off with steps lasting 1 second each. Wait until the relay falls off or the electric valve closes again and immediately release the button. The second step up before the button was released will be used.
If you reprogram the duration of the timer, the PWM configuration will be reset to 100%.
How to build it yourself
A small programmable microprocessor (ATtiny45) is used for this project, which needs to be programmed. You need to have a compiler (Arduino-IDE works fine) and a suitable programmer.
The build it yourself project (schematic diagram and software) will be presented shortly on GitHub.
Ordering
We are ordering a few ready to use Timers and they should become available soon. Prices will be around 35 Euro's. We don't know how fast they will go, if you want to reserve one or more units, just let us know.
