Stupid MSC to 2.4GHz Question

[wintersdawn 176]

This is probably a stupid question to ask but I am so ignorant of mechanical speed controllers.

Is it possible to use a vintage MSC with a 2.4GHZ receiver?

Will the MSC pictured below have a battery connector to give the 2.4GHZ receiver power?

Cheers

p.s. this item is on its way to me so I can't test yet and wanted to get some info first.

[Fabia130vRS 2098]

As far as I know it should work as the reciever communicates to the transmitter over 2400MHz frequency and the servo talks to the MSC.

[ewant81 33]

If your receiver has at least 2 channels (I think 2 channels is the minimum), then you can run the two servos from the receiver no problem. One servo (channel 1) is your steering, and the other servo runs your MSC on channel 2.

MSCs are pretty simple and robust, but they aren't infallible. If in the future you want to swap to an ESC then that also is realtively easy to do.

[wintersdawn 176]

Thanks for the info, much appreciated.

I have a memory of a battery pack with 2 AA batteries needed to power 'something' when using a mechanical speed controller?

[Juhunio 6830]

Note of caution, from personal experience  

If you plug a modern 7.2V battery into the MSC, then plug the MSC into a standard 2.4GHz receiver, you will fry the receiver which (I believe) generally has a max voltage rating of 6.6V. A modern ESC handles that voltage step down in the BEC, and there is no BEC in an MSC

You either need to use the separate MSC battery pack for the receiver, or an in-line BEC

You might be completely aware of this, but just in case...

[ewant81 33]

1 minute ago, Juhunio said:

Note of caution, from personal experience  

If you plug a modern 7.2V battery into the MSC, then plug the MSC into a standard 2.4GHz receiver, you will fry the receiver which (I believe) generally has a max voltage rating of 6.6V. A modern ESC handles that voltage step down in the BEC, and there is no BEC in an MSC

You either need to use the separate MSC battery pack for the receiver, or an in-line BEC

You might be completely aware of this, but just in case...

Has this changed with modern receivers? I'm not yet up to speed with 2.4GHz systems, and on my old crystal receiver it had BEC circuitry built in.

[Juhunio 6830]

2 minutes ago, ewant81 said:

Has this changed with modern receivers? I'm not yet up to speed with 2.4GHz systems, and on my old crystal receiver it had BEC circuitry built in.

I believe that’s right. Old receivers had the BEC, new receivers don’t. These days it’s in the ESC

Someone with more technical knowledge than me might be able to be more specific,  but my personal experience is that if you plug a 7.2v battery into an MSC and then a modern 2.4ghz receiver, the receiver goes fizz pop smokey dead 😕

[wintersdawn 176]

10 minutes ago, Juhunio said:

Note of caution, from personal experience  

If you plug a modern 7.2V battery into the MSC, then plug the MSC into a standard 2.4GHz receiver, you will fry the receiver which (I believe) generally has a max voltage rating of 6.6V. A modern ESC handles that voltage step down in the BEC, and there is no BEC in an MSC

You either need to use the separate MSC battery pack for the receiver, or an in-line BEC

You might be completely aware of this, but just in case...

Thanks for the info, I was going to use an Austar or DumboRC transmitter/receiver combo but maybe the MSC will not reduce the voltage to a safe level for these receivers?  I've got a TEU101BK ESC but was going to try the MSC but maybe better not.

[ewant81 33]

7 minutes ago, Juhunio said:

I believe that’s right. Old receivers had the BEC, new receivers don’t. These days it’s in the ESC

Someone with more technical knowledge than me might be able to be more specific,  but my personal experience is that if you plug a 7.2v battery into an MSC and then a modern 2.4ghz receiver, the receiver goes fizz pop smokey dead 😕

Yes, that would be very expected if there isn't something to cut down the voltage!

 

5 minutes ago, wintersdawn said:

Thanks for the info, I was going to use an Austar or DumboRC transmitter/receiver combo but maybe the MSC will not reduce the voltage to a safe level for these receivers?

If the receiver has BEC (battery eliminator circuitry) it's bound to tell you on the packaging. You might be able to find a 2.4GHZ receiver that has that built-in? This appears to have a BEC receiver but I would check with product manuals/supplier. (https://www.fusionhobbies.com/product/c500053-carson-reflex-pro-3-2-channel-2-4ghz-radio)

From my bad memory, you can power the receiver with it's own battery pack and then to disable the power supply from the MSC it should be a case of removing a pin from the MSC->receiver connection.

I'm sure someone with more definite knowledge will be along shortly!

[wintersdawn 176]

5 minutes ago, ewant81 said:

Yes, that would be very expected if there isn't something to cut down the voltage!

 

If the receiver has BEC (battery eliminator circuitry) it's bound to tell you on the packaging. You might be able to find a 2.4GHZ receiver that has that built-in? This appears to have a BEC receiver but I would check with product manuals/supplier.

From my bad memory, you can power the receiver with it's own battery pack and then to disable the power supply from the MSC it should be a case of removing a pin from the MSC->receiver connection.

I'm sure someone with more definite knowledge will be along shortly!

Thanks will check for built-in BEC in either the DumboRC or Austar receivers.

[wintersdawn 176]

So I guess an old Acoms 27mhz receiver with built-in BEC would handle 7.2v from the ESC through a battery lead/connection to the receiver and so not require a AA battery pack to power the receiver?  From what era were these AA battery packs needed?  Cheers.

[El Gecko 1344]

Let's clear some of this up, because there's a lot of conflicting info.

The car on its way to you has an MSC, two servos, and a battery box that will house 4 AA size batteries.

Judging from the plug setup in your pic, it looks like there may already be a receiver in the car.

The receiver will be powered by the 4AA battery box, which will also power the servos.

The MSC is just a switch plate for the big battery--the direction and power of the big battery to the motor is switched by one of the servos.

The 4AA box, receiver, and servos are on the same circuit, which should be completely separate from the large 7.2V battery. (I have never seen an MSC with an Rx power plug, but who knows what kind of funky stuff is out there)

You can remove the old receiver and install a new 2.4G receiver to match your transmitter, as long as you plug the servo and battery box into the new receiver the same way they're plugged into the old one.

The new receiver will run off the 4AA battery box exactly the same as the old one. And the car will work exactly the same as it would have with the old receiver. You can even keep the ON/OFF switch in the same location.

If, in the future, you decide to install an ESC, you will have to remove the MSC switch plate, the servo that powers the MSC switch plate, and the 4AA battery box. Then just keep the steering servo plugged into the new receiver, and plug in the new ESC in place of the old servo (no extra batteries will be needed) and you will be all good to go.

[ewant81 33]

20 minutes ago, wintersdawn said:

So I guess an old Acoms 27mhz receiver with built-in BEC would handle 7.2v from the ESC through a battery lead/connection to the receiver and so not require a AA battery pack to power the receiver?  From what era were these AA battery packs needed?  Cheers.

Yes, that's correct.

You can also use a separate battery pack with 4AA batteries to power the Acoms 27MHz receiver, and in that case you would pull a pin from the MSC-> receiver cable (usually the red lead with Tamiya wiring) to not supply the 7.2V from tha main battery.

[wintersdawn 176]

7 minutes ago, El Gecko said:

Let's clear some of this up, because there's a lot of conflicting info.

The car on its way to you has an MSC, two servos, and a battery box that will house 4 AA size batteries.

Judging from the plug setup in your pic, it looks like there may already be a receiver in the car.

The receiver will be powered by the 4AA battery box, which will also power the servos.

The MSC is just a switch plate for the big battery--the direction and power of the big battery to the motor is switched by one of the servos.

The 4AA box, receiver, and servos are on the same circuit, which should be completely separate from the large 7.2V battery. (I have never seen an MSC with an Rx power plug, but who knows what kind of funky stuff is out there)

You can remove the old receiver and install a new 2.4G receiver to match your transmitter, as long as you plug the servo and battery box plugs into the new receiver the same way they're plugged into the old one.

The new receiver will run off the 4AA battery box exactly the same as the old one. And the car will work exactly the same as it would have with the old receiver.

If, in the future, you decide to install an ESC, you will have to remove the MSC switch plate, the servo that powers the MSC switch plate, and the 4AA battery box. Then just keep the steering servo plugged into the new receiver, and plug in the new ESC in place of the old servo (no extra batteries will be needed) and you will be all good to go.

Thanks for this valuable info, will digest, MSC set-up's are beyond my experience as I've only ever dealt with ESC set-ups.

[JennyMo 3526]

What El Gecko says above makes sense... most importantly, the last sentence.

It's not the 1980s anymore - unless this was an original Porsche 959* - I would junk the MSC, second servo and A4 battery holder along with the 27Mhz Tx/Rx and fit an ESC - far simpler, smaller, lighter weight electronics package, and far less likely to go wrong... remember those days when the A4 batteries would conk out and the MSC would jam full-on... not good times!

*personally speaking, even if I did have an original 959, if I ever wanted to run it I'd use modern electronics inside it, and keep the original stuff in a box.

The last thing you want is your 'vintage' model going on the fritz and crashing due to antiquated electronics.

Jenny x

[wintersdawn 176]

1 minute ago, ewant81 said:

Yes, that's correct.

You can also use a separate battery pack with 4AA batteries to power the Acoms 27MHz receiver, and in that case you would pull a pin from the MSC-> receiver cable (usually the red lead with Tamiya wiring) to not supply the 7.2V from tha main battery.

Cheers

[wintersdawn 176]

6 minutes ago, JennyMo said:

What El Gecko says above makes sense... most importantly, the last sentence.

It's not the 1980s anymore - unless this was an original Porsche 959* - I would junk the MSC, second servo and A4 battery holder along with the 27Mhz Tx/Rx and fit an ESC - far simpler, smaller, lighter weight electronics package, and far less likely to go wrong... remember those days when the A4 batteries would conk out and the MSC would jam full-on... not good times!

*personally speaking, even if I did have an original 959, if I ever wanted to run it I'd use modern electronics inside it, and keep the original stuff in a box.

The last thing you want is your 'vintage' model going on the fritz and crashing due to antiquated electronics.

Jenny x

Thanks Jenny for the info, the model is a 1995 Tamiya Hummer.

[El Gecko 1344]

7 minutes ago, wintersdawn said:

Thanks for this valuable info, will digest, MSC set-up's are beyond my experience as I've only ever dealt with ESC set-ups.

You just have to think of MSC setups as two distinct systems in the car, working together through the MSC. Instead of everything tied into the main 7.2V battery (receiver, steering servo, ESC), you have the "motor system" and the "radio system" that are electrically separate in an MSC car.

The radio system is the control system: receiver and servos for steering and throttle control, powered by the 4AA battery box. Then you have the motor system which is literally just the big battery and the motor, with the position of the MSC plate determining how much power the motor gets and which direction it goes.

[wintersdawn 176]

2 minutes ago, El Gecko said:

You just have to think of MSC setups as two distinct systems in the car, working together through the MSC. Instead of everything tied into the main 7.2V battery (receiver, steering servo, ESC), you have the "motor system" and the "radio system" that are electrically separate in an MSC car.

The radio system is the control system: receiver and servos for steering and throttle control, powered by the 4AA battery box. Then you have the motor system which is literally just the big battery and the motor, with the position of the MSC plate determining how much power and which direction the motor goes.

Cheers for the info.  So any set-up with a MSC will have a 4AA battery box powering the receiver and servo's with the receiver-to-servo/channel 1 controlling left/right and receiver-to-servo/channel 2 for throttle which when changed on the transmitter will change the position of the MSC selector/plate for either forward or reverse and the 7.2v battery just providing power to the motor? (which is probably what you just said!)

[ewant81 33]

49 minutes ago, El Gecko said:

You just have to think of MSC setups as two distinct systems in the car, working together through the MSC. Instead of everything tied into the main 7.2V battery (receiver, steering servo, ESC), you have the "motor system" and the "radio system" that are electrically separate in an MSC car.

The radio system is the control system: receiver and servos for steering and throttle control, powered by the 4AA battery box. Then you have the motor system which is literally just the big battery and the motor, with the position of the MSC plate determining how much power the motor gets and which direction it goes.

I'm not sure if you are simplifying the picture here because it's easier to understand, or that you aren't aware that some receivers that have builtin BEC functionality?

I have a car with an MSC and a receiver with BEC functionality. I don't need the 4AA box as the receriver can correctly cut-down the voltage to what it needs. If I wanted I could easily switch to using the 4AA pack to power the receiver, pull the power line from the MSC-> receiver and work it that way, but it's not the only solution.

Here is the wiring guide for an old Acoms receiver with BEC  

[El Gecko 1344]

41 minutes ago, wintersdawn said:

Cheers for the info.  So any set-up with a MSC will have a 4AA battery box powering the receiver and servo's with the receiver-to-servo/channel 1 controlling left/right and receiver-to-servo/channel 2 for throttle which when changed on the transmitter will change the position of the MSC selector/plate for either forward or reverse and the 7.2v battery just providing power to the motor? (which is probably what you just said!)

Yes, exactly! The servo on the 2nd channel changes the position of the MSC plate, which makes it contact different points on the base, giving the motor different directions and speeds (some of those contact points are hooked up to the resistor(s), to provide lower-power/speed throttle options).

[El Gecko 1344]

37 minutes ago, ewant81 said:

I'm not sure if you are simplifying the picture here because it's easier to understand, or that you aren't aware that some receivers that have builtin BEC functionality?

I have a car with an MSC and a receiver with BEC functionality. I don't need the 4AA box as the receriver can correctly cut-down the voltage to what it needs. If I wanted I could easily switch to using the 4AA pack to power the receiver, pull the power line from the MSC-> receiver and work it that way, but it's not the only solution.

Here is the wiring guide for an old Acoms receiver with BEC  

I was describing the typical MSC setup. Yours is clearly different, as I have never seen an MSC with an extra power plug for the receiver. This makes it function basically the same as an ESC. Except with two plugs in the receiver for the MSC (servo plug, battery plug) instead of just one in the servo channel for the ESC.

All 2.4G receivers should have BEC built in, so even if this is the case on OP's car, it should be no problem to just plug the old switch harness right into the new receiver, same as the old setup.

[Fabia130vRS 2098]

1 hour ago, JennyMo said:

What El Gecko says above makes sense... most importantly, the last sentence.

It's not the 1980s anymore - unless this was an original Porsche 959* - I would junk the MSC, second servo and A4 battery holder along with the 27Mhz Tx/Rx and fit an ESC - far simpler, smaller, lighter weight electronics package, and far less likely to go wrong... remember those days when the A4 batteries would conk out and the MSC would jam full-on... not good times!

*personally speaking, even if I did have an original 959, if I ever wanted to run it I'd use modern electronics inside it, and keep the original stuff in a box.

The last thing you want is your 'vintage' model going on the fritz and crashing due to antiquated electronics.

Jenny x

I am thankful I could witness this phenomenon

my dt01 fighter buggy came with a MSC and my first years relied on the MSC. Later a LRP brushed esc was a mindblower

[KEV THE REV 2319]

I would also go with the ESC and you could possibly - space permitting - keep the MSC as a dummy - non working , just for effect ,  and fit the ESC somewhere else , maybe where the AA pod was ?

[Wooders28 4723]

Before BEC, I used to solder a lead, with a zener diode onto the infeed battery contact ,under the MSC, and power the reciever off that.

It worked, but as the diode dropped the voltage, it meant that when the battery was almost flat, it still had enough power to drive, but not operate the servos. They where going slower than walking pace, so wasn't a major issue.