Many late model electromechanical (EM) pinball machines feature and end of ball bonus where a bonus accumulated during the current ball in play is counted down and added to the player's score when the ball drains. Many of these bonus counts can be doubled by reaching certain objectives, or on the last ball, etc. This page demonstrates how the single vs. double bonus values are added to the player's score.
A typical implementation of the single and double bonus count from a 1976 Bally Night Rider schematic diagram is shown here although similar circuits were used by other manufacturers:
On the left are two circuits that drive the Bonus Unit Reset Sol. (solenoid). (The Bonus Unit is a step unit.) In the center is part of the circuit for the 1000 Point Re. (relay). In the lower right corner is a Sequence chart from the schematic that shows when each of the Score Motor cam switches activates relative to each other.
Below is a simplified version of the circuits above that will be used in the circuit animations.
On the left is the Sequence chart. In the center are the circuits for the 1000 Point relay and Bonus Unit Reset (or Subtract) solenoid along with the Bonus Score relay and Score Motor required by parts of the circuit. On the right are representations of the Bonus Unit and the 1000 Point Score Reel. In the lower right are extra switches used to manipulate the simulation.
On this and many other games, a single bonus is counted at a rate of 5000 points (or 5 pulses) per Score Motor cycle. The Score Motor sends 5 pulses to the 1000 point relay and 5 pulses to the Bonus Unit Subtract solenoid. There is effectively one Bonus Unit Subtract pulse for each 1000 point relay pulse so the Bonus Unit steps down each time the Score Reel advances.
A double bonus is counted at 4000 points (or 4 pulses) per Score Motor cycle. While the 1000 point relay gets 4 pulses per Score Motor cycle the Bonus Unit Subtract solenoid gets just 2 pulses per Score Motor cycle. The effect is that there are two 1000 point pulses for each Bonus Unit Subtract pulse, or double the number of scoring pulses, so the Score Reel advances twice each time the Bonus Unit steps down.
The single bonus animation starts when the current ball in play drains and closes the Out Hole switch. Notice that the Bonus Unit has been advanced to position 4 indicating that the player is due 4000 points at the end of the ball.
Single Bonus animation
As soon as the Out Hole switch closes, it fires the Bonus Score relay which in turn closes a switch that starts the Score Motor turning. As the Score Motor rotates it closes switches that send pulses into the bonus count circuits. As the Score Motor rotates through a 180 degree cycle,
This process repeats four times as the switches on the #2 Score Motor cam close. This steps the Bonus Unit down (from 4 to 0) and steps the 1000 Point Score Reel up (from 0 to 4) as the pulses from the #2 cam pass through the circuits.
Once the Bonus Unit reaches zero, it opens a switch in the Bonus Score relay circuit which allows it to relax. The Bonus Score relay in turn opens a switch in the 1000 Point relay circuit that prevents any more pulses from the Score Motor to reach the 1000 Point relay. The bonus count ends after 4 pulses or 4000 points so the 5th pulse from the Score Motor #2 cam switch is ignored.
The animation for the double bonus count picks up where the single bonus count animation left off. Notice that the 1000 Point Score Reel is still at 4. Notice also that the Bonus Count has been advanced to 2 during the current ball and that the Double Bonus switch has been activated (exactly how doesn't matter).
Double Bonus animation
This animation starts out the same way, with the Out Hole switch closing to activate the Bonus Score Relay and Score Motor. However the two Make/Break switches controlled by the Double Bonus are now in the opposite position so pulses from the Score Motor #2 cam are all ignored. Instead, as the Score Motor turns:
So half way through the Score Motor cycle, the 1000 Point relay and Score Reel have activated twice, but the Bonus Unit has only reset one position. The process above repeats a second time using switches on Score Motor cams #6, #7 & #8 to advance the Score Reel (from 6 to 8) and reset the Bonus Unit (from 1 to 0).
Follow these links to other animated schematic diagrams: