Soundguy
Old Timer
- Joined
- Mar 11, 2002
- Messages
- 51,575
- Location
- Central florida
- Tractor
- RK 55HC,ym1700, NH7610S, Ford 8N, 2N, NAA, 660, 850 x2, 541, 950, 941D, 951, 2000, 3000, 4000, 4600, 5000, 740, IH 'C' 'H', CUB, John Deere 'B', allis 'G', case VAC
The bypass type used to be common.
You have the 2 large lugs for battery, and starter. then you have 2 small lugs.
One lug is for switched power to the coil.. The other end of the coil is tied to the mounting leg on the solenoid. The other small post will become 'hot' when the solenoid is energized. The reason it is called a 'bypass' type is because 'way back when'.. lots of tractors and vehicles used an ignition resistor in line with the coil. For instance.. the car may have a 6v coil, dropping resistor, and a 12v electrical system. During starting.. power at the battery coupld drop low.. like 8-10v.. once you ad din the drop from the ignition resistor.. there was not always sufficient power to the coil for reliable starts. You hook the line from the bypass terminal to the coil.. thus when you energize the solenoid, you pass battery power directly to the coil for a short period of time while the starter is turning over and system votlage is low. This momentarilly puts 8-10v on the 6v coil for extra hot sparks for a second or so.. ( doesn't hurt anything).
If you look at this as a relay, then, the bypass unit is a DPST .
( double pole, single throw )..
( one pole is the high current portion.. the other pole is the low current feeding the bypass terminal )
An isolated solenoid is a SPST switch.
The reason it is called 'isolated', is because the coil contacts are isolated from the mounting base.
If you want to add more junk tot he fire, electrically speaking.. the contacts on the dpst, and the spst are "NO" ... ( normally open ). If the relays were double throw, instead of single throw, then they may have a common post, and a set of 'NO', and a set of 'NC' contacts.. ( nc=normally closed )
Soundguy
You have the 2 large lugs for battery, and starter. then you have 2 small lugs.
One lug is for switched power to the coil.. The other end of the coil is tied to the mounting leg on the solenoid. The other small post will become 'hot' when the solenoid is energized. The reason it is called a 'bypass' type is because 'way back when'.. lots of tractors and vehicles used an ignition resistor in line with the coil. For instance.. the car may have a 6v coil, dropping resistor, and a 12v electrical system. During starting.. power at the battery coupld drop low.. like 8-10v.. once you ad din the drop from the ignition resistor.. there was not always sufficient power to the coil for reliable starts. You hook the line from the bypass terminal to the coil.. thus when you energize the solenoid, you pass battery power directly to the coil for a short period of time while the starter is turning over and system votlage is low. This momentarilly puts 8-10v on the 6v coil for extra hot sparks for a second or so.. ( doesn't hurt anything).
If you look at this as a relay, then, the bypass unit is a DPST .
( double pole, single throw )..
( one pole is the high current portion.. the other pole is the low current feeding the bypass terminal )
An isolated solenoid is a SPST switch.
The reason it is called 'isolated', is because the coil contacts are isolated from the mounting base.
If you want to add more junk tot he fire, electrically speaking.. the contacts on the dpst, and the spst are "NO" ... ( normally open ). If the relays were double throw, instead of single throw, then they may have a common post, and a set of 'NO', and a set of 'NC' contacts.. ( nc=normally closed )
Soundguy
