The Engineer

There is no information about this IC anywhere on the internet. Not to worry I have worked it out by tracing the circuit. I found the pin that carries the demodulated output from the receiver so I can use my own data formats. Mike

I bought a couple of old 27MHz 2-channel AM receivers to play with. One is an HPI RF-1, the other a Hobao HR-201. Both receivers use the same circuit board with a P8196R integrated circuit. Does anyone have a data sheet for this please? What is the supply voltage and which are the positive and negative pins on the supply connector? Thanks! Mike

If you don't mind that would be very helpful, thank you. I found these online which have all the correct dimensions but they are advertised for boats and the motor speed is 8224rpm at 12V. Not sure if that's what I need for this vehicle. https://www.switchelectronics.co.uk/products/mfa-719re-280-1-12-24v-3-pole-dc-motor-8224rpm Mike Update: I calculated the gearbox reduction ratio as 20: 1 which gives a track drive wheel speed of 7 revs per second. Is that reasonable?

OK it looks as though I was in the wrong forest barking up the wrong tree 😒. The brushed motors are clapped out. Can someone advise me on a replacement for these please? The body measures 30mm long x 24mm diameter and the shaft is 2mm diameter. The motors run off a 9.6V NiCd battery pack. What voltage motor should I buy and any idea what speed it should be for a tracked vehicle? Mike

Yes thanks. I should have dug further before posting 😕. I found an explanation about the inductors here: https://electronics.stackexchange.com/questions/648373/inductors-at-a-dc-motors-terminals Mike

Thanks for the reply. I thought it might be a resistor but the good ones measure 0.4 ohms and the markings (blue grey brown) denote 680. As it's toast I cut it open and discovered it's an inductor, presumably 680uH. I found a source on eBay so should be running again soon. Mike

One of the motors in the missile launcher I'm repairing stopped working because a component in its supply lead has burnt out. I thought it might be an inductor but the motor draws 1.5 amps which seems a bit high for an inductor this size. The remaining components measure 0.4 Ohms. Any ideas please? Mike

Hello everyone, my first post here. I'm trying to repair a missile launcher which I bought second hand for my grandson but it's driving me nuts and I need some help from a technical expert! The transmitter is a simple 27MHz circuit with a single transistor crystal oscillator feeding a single transistor modulator, driven by a PT8A9701 encoder. The receiver is a single transistor feeding into a PT8A973 decoder. The first problem was lack of range. The telescopic aerial was broken so I replaced it, together with the transistors in the transmitter and receiver. I adjusted the receiver tuning coil and it now has a reasonable range and responds to the buttons that play sound effects and launch missiles. However it only responds intermittently to commands that control the motors. Changing the encoder and decoder ICs didn't help. If I monitor the output of the receiver that feeds into the decoder I get a continuous stream of PWM data, but the corresponding decoder output that feeds the motors either remains low or only goes high occasionally. The motor circuits are fine - connecting 3V to the base of the driver transistors has them spinning round nicely. The transmitter and receiver circuits are as per this data sheet: https://www.diodes.com/assets/Datasheets/PT8A9701973973L.pdf If anyone has any ideas on where I can look for the fault I'd be very grateful as I am completely baffled. Mike