Timer Circuit power question

[Colin]

I recently purchased a 555 Astable switch kit from Maplin (cat no N33FL)

https://www.maplin.co.uk/p/555-astable-switch-kit-n33fl

I want to use it to simulate a Machine gun. The output should cause a white LED to flash (it would be nice if I could drive a speaker too )
The kit specifies a 12V DC supply. Would it be possible to tweak the circuit to run from 6V instead and could I drive the LED directly from the Relay driver output? (the LED has already been wired up with a suitable resistor)

[tetsujin]

I recently purchased a 555 Astable switch kit from Maplin (cat no N33FL)

https://www.maplin.co.uk/p/555-astable-switch-kit-n33fl

I want to use it to simulate a Machine gun. The output should cause a white LED to flash (it would be nice if I could drive a speaker too )
The kit specifies a 12V DC supply. Would it be possible to tweak the circuit to run from 6V instead and could I drive the LED directly from the Relay driver output? (the LED has already been wired up with a suitable resistor)

Should be, yes. Though without a schematic on that page it's tough to say for sure.

You may want to remove the relay if you do that, though: the coils in a relay can build up a significant amount of charge, and when the magnetic field collapses this can inject a bunch of current into the circuit. Normally a relay circuit has a diode on the relay's coil connection so this surge of current can simply flush itself away through the diode. (Again, with no schematic I can't tell if they provided this. I assume they did...) And, of course, a relay makes some noise and you may prefer not to have that going on...

[Colin]

Ok, the datasheet is here

https://maplindownloads.s3-eu-west-1.am ... t-6735.pdf

Also, is there any way of increasing the flash frequency to say 2Hz from the current limit of 1Hz?

[tetsujin]

Ok, the datasheet is here

https://maplindownloads.s3-eu-west-1.am ... t-6735.pdf

Also, is there any way of increasing the flash frequency to say 2Hz from the current limit of 1Hz?

The oscillation rate is governed by the charge/discharge rate of the capacitor C1. So you either need a lower capacitance (so the existing current can fill the capacitor more quickly), or reduce the resistance feeding it (so, replace R4 and R5 probably.)

In case you're not too familiar with capacitors, you'd want a capacitor with lower capacitance (lower Farad rating) but the same voltage. I'd imagine the existing C1 has a voltage rating of 25V or higher... A change in voltage rating doesn't affect how the capacitor behaves in the circuit, it determines how much charge the capacitor can hold before it blows up. The capacitance rating is the relationship between how much charge is in the capacitor, and how much voltage is across the capacitor. (In some situations it's like "how much electro-motive force you need to push more charge into the capacitor", and the voltage limit is "how hard you can push before it breaks". A common rule of thumb is to have that device-failure limit be double the values you'd actually expect to see in the circuit - so since it's a 12V circuit I figured the cap would be rated to 25V or higher.)

Half the capacitance should double the frequency. Or half the resistance should also double the frequency.

Though for the cost of this board (and particularly since you don't need the relay) you could just use a microcontroller. Something like the Adafruit Trinket M0 or the Arduino Pro Mini would both be comparable in price to this 555 board (though you'd need a USB-to-TTL serial interface for the Pro Mini)

[Colin]

I already have the 555 kit