The first revision board, designated by no markings, has a photocell trigger circuit utilizing a 555 timer chip. This circuit, with the change and addition of a couple of components, can be used as a timed trigger for the sound chip. This circuit will then trigger at the designated time interval. With the components specified you can get a few minutes delay. Different values of R8 and C6 will produce longer delays.
Replace R8 with a 500k potentiometer and C6 with a 220uf 16v electrolytic capacitor. The 500k ohm pot must be modified from 3 leads to two. Connect the center wiper lead to one of the outer leads. These combined leads go to the R8 hole near the top of the board and the single lead goes to the R8 hole adjacent to C6. This pot controls the time delay.
The final mod is to jumper from R4, hole closet to the LED, to J6-2. A short piece of 30 ga insulated wire is sufficient for the jumper. Add a 0.1uf ceramic capacitor between U4-1 and U4-2. Place this capacitor flat on the solder side of the board between the leads of U4.
With the time delay circuit in place J8 must be jumpered on 1-2 for single play and J7 must be jumpered on 2-3. LED D2 will still indicate when the sound chip is being triggered and help with setting the time delay.