Well this is just one of three projects that i have been tinkering with to get me prepared for the real ROBOT stuff.

The Main Chassis :-

Iis an old Maplins R/C 4X4 Monster truck that I bought 16 years ago and has sat in my daughters' bedroom for many a year.


Project Road Map:-

The concept is to make the truck as autonomous as possible without having to resort to using a microcontoller . it must also  DO more than travel across the floor.

A} switch on Headlights & tail lights if it goes into a shadowed area.

B} turn on indicators if turning left or right

C}  turn on Reversing lights if reversing and sound bleeper as warning

D} on approaching an object turn on wig/wag headlights

E} on closer approach turn on siren & turn on Police style roof bar lights

F} automatically reverse away on acurved course after a collision, pause and then go forward again.

G} During the pause Brake lights should come on

H} Stop immediatly if any wheel is in danger of going over a precepice and drive away from the Danger

I} all of this hopefully with analogue sensors and NO microcontoller


10mm LED's bright white installed on chassis as Head lights.









Amber Flashing LED's as Indicators mounted on the body work,

Red  LED Brake lights fitted as are the Red RED tail lights,

Reversing LEDs are Bright white.

LDR sensor fitted into the "blower" housing on the hood (the shiny bit in the middle )








Darkness sensor with 9V relay built & tested

Headlamp Wig-Wag (Flip Flop transistor circuit) built & tested

Police style Hazard bar circuit designed & tested.















In the above picture you can see the LDR hidden in the "blower" shroud & the police light flashing RED


In the picture below you can see the Police light flashing BLUE








too much to list LoL,  but the research and breadboarding is fun BUT waiting for parts is NOT

Thanks to:-

Well this site obviously :-}

Talking site & owner for making my research that much easier and sharing the circuits for free !

To my long time friend Mark, owner of  ,for his long standing patience with answering dumb electronic based questions when my brain refuses to remember stuff I did 40 years ago.

Brentford Radio Control for the helpful hints on Police colours & stickers

Last but by no means least Camala (my lovely wife of nearly 30 years ) for helping me come to terms with my failing health and indulging me in this "new" hobby. Also to my two daughter Samantha Jane and Megan  Annalise for loaning me the Truck and  "Dad can you talk about something else PLEASE "

Embedded video:
See video
See video


Y-Geo's picture

Robotruck update


 well a week has passed and not a lot done thanks to our health care service messing me about 3 days of this week.

 I did get the two mini grill lights with the 1.8mm red/blue flashing lights of our police " Q" cars done I will put up pics when i find my camera again.

Madam has taken the time of me being in Hospital to "tidy" up which means completely wrecking my memory of where i put my stuff to hand. Grr.


Today I want to finish the LH police roof bar lights, LED's are in place but the wiring is not................

I want to test the siren on the breadboard and see how that works out.

At some point I am supposed to make dinner as madam is on a double shift at the hospital as they have the usuall suspects on "sick" leave doing their last minute shopping no doubt or too hung over to work. Thank God christmas is only once per year although it seems to take over for longer as well.



Anonymous's picture


Hah - if I don't recognize the mess on the table, the names of the wife and kids were enough to fill in the gap :-).

The LDR is strong enough to directly drive a decent transistor like a 2N1711 (if I recall correctly - doing this off the top of my head), but I prefer a Darlington construction anyway (more or less simulated in your design).

Rex's picture

So this is what you've been

So this is what you've been working on.

I'll look forward to seeing the finished product.


Smoke 'em if you got 'em!

Y-Geo's picture



   Bit hard to print out a schematic from the "old grey stuff" <BG>

Basically if you look at the 3 files  to see what I " borrowed" for using to flesh out my ideas  .

 The flip/flop (multivibrator transistor cct ) controls the wig -wag headlight circuit, the dark detector cct is a copy of a german design using an LDR with 2 PNP transistors to "drive" the relay that turn on the driving lights when the truck goes into shadow.

The police hazard lights for the roof bar is a cut down version of the multi-LED cct where the LEDS are 'plexed by a 555 chip

A word of caution 555 chips burm 20mA standing doing naff all so use the CMOS version of the 555 which burns µA's

As the rest of the build progresses so I will post the clues to adapting stuff.


If you want to know why no "brain" as such look up the work of  Alan Turrin & Tommy Flowers at Bletchley park (Station 10 or as most people think X )

I read up that work whilst in a 3rd world backwater then used their concept to have a"computerised" control on a very dangerous and dirty machine. Basically a set of relays that when certain safe criteria were met the machine could be started but with the "lock outs" not  met no starting was allowed. I thought it was hilarious when the Minister of industy & Commerce plus the Chairman of the Industrial Developement corp turned up with their flunkies in tow to Oooh  & Aaaah at it LoL

 here is link to make you think what this sensor could be used for:-


Good Hunting

Anonymous's picture

First of all very nice

First of all very nice hack.
Could you post complete schematic for this robot ?

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