Step down warning alarm
I have a habit of driving the motorhome out of a campsite without putting the step up. Usually someone waves a warning but I have driven for quite a way with the darn thing down and even hit it on a curb once.
I set up a little circuit to generate a warning tone if the engine is running with the step down.
A battery is connected through a resistor and switch to a 6 volt tone generator. Current draw was about 25 mA and a 220 ohm resistor served nicely to bring the battery voltage down to the tone device, providing a hard to ignore squeal.
I tried a magnetic switch first, but the MH step has a bit of play in it - too much to count on bringing a magnet close enough to the switch without hitting it. Luckily I found the microswitch with long stiff spring attachment. It was from a surplus store years ago. If anyone knows where to get them now, I would sure like to know. I had a dozen of them when I was teaching electricity to junior high students but loaned them to another teacher and lost them. The switch needs to be momentary contact with a normally open connection. Any DPST or DPDT microswitch could be made to work with a stiff spring attachment.
The switch with its handy sheet metal mount attached was easily attached to the top of the step frame with a couple of wood screws.
Note the spring extension in the way of the step as it is pushed in.
For power with ignition key on, I searched the inside cab fuse panel and quickly found an unused fuse position. I played around with a fuse and got a wire soldered onto one side of it - but the heat melted the fuse wire. I found the very thing in a store near the fuse display.
I wondered why it had jacks for two fuses. It is designed to add another load to a fuse in use and the first fuse limits current to both the existing load in the fuse panel and the new load; the second is just for the new external load. Five amps was the smallest fuse I had after melting my 2 amp one. Anyway, the resistor limits the current to about 50 mA so the fuse is only necessary if the resistor happens to short itself.
I ran the power wire across the cab just behind the seats and is covered with carpet/mat most of the way. The alarm is in an unused corner beside DW's seat and very close to house door, making the alarm suggest something wrong over that way. There happened to be a tiny hole in the floor and caulking beneath that spot under the vehicle so I just pushed the ground wire through and connected it to the switch. I used push on connectors on the alarm so it can be easily disconnected if something goes wrong.
It works beautifully!
I set up a little circuit to generate a warning tone if the engine is running with the step down.
A battery is connected through a resistor and switch to a 6 volt tone generator. Current draw was about 25 mA and a 220 ohm resistor served nicely to bring the battery voltage down to the tone device, providing a hard to ignore squeal.
I tried a magnetic switch first, but the MH step has a bit of play in it - too much to count on bringing a magnet close enough to the switch without hitting it. Luckily I found the microswitch with long stiff spring attachment. It was from a surplus store years ago. If anyone knows where to get them now, I would sure like to know. I had a dozen of them when I was teaching electricity to junior high students but loaned them to another teacher and lost them. The switch needs to be momentary contact with a normally open connection. Any DPST or DPDT microswitch could be made to work with a stiff spring attachment.
The switch with its handy sheet metal mount attached was easily attached to the top of the step frame with a couple of wood screws.
Note the spring extension in the way of the step as it is pushed in.
For power with ignition key on, I searched the inside cab fuse panel and quickly found an unused fuse position. I played around with a fuse and got a wire soldered onto one side of it - but the heat melted the fuse wire. I found the very thing in a store near the fuse display.
I wondered why it had jacks for two fuses. It is designed to add another load to a fuse in use and the first fuse limits current to both the existing load in the fuse panel and the new load; the second is just for the new external load. Five amps was the smallest fuse I had after melting my 2 amp one. Anyway, the resistor limits the current to about 50 mA so the fuse is only necessary if the resistor happens to short itself.
I ran the power wire across the cab just behind the seats and is covered with carpet/mat most of the way. The alarm is in an unused corner beside DW's seat and very close to house door, making the alarm suggest something wrong over that way. There happened to be a tiny hole in the floor and caulking beneath that spot under the vehicle so I just pushed the ground wire through and connected it to the switch. I used push on connectors on the alarm so it can be easily disconnected if something goes wrong.
It works beautifully!
