Old motor

TLyttle · Nov 04, 2009, 12:14 AM

A buddy left me an old Simprop Pfalz kit, and I have a question about the motor: does it have internal capacitors, or do I need to add my own? It is a Simprop Speed 280, mounted in a ParcDrive 300+ gearbox. The instructions for the motor are in German... French, maybe; German, no chance!

groundfx · Nov 04, 2009, 01:08 AM

Quote:

Originally Posted by TLyttle

A buddy left me an old Simprop Pfalz kit, and I have a question about the motor: does it have internal capacitors, or do I need to add my own? It is a Simprop Speed 280, mounted in a ParcDrive 300+ gearbox. The instructions for the motor are in German... French, maybe; German, no chance!

I just bought an old Czech kit on sale that has a similar 280 setup. It came with a small bag of 2 caps that I had to solder on.

Even if yours has internal caps, it doesn't hurt to add more. I'd just add them and be done with it.

vintage1 · Nov 04, 2009, 04:55 AM

just add three caps anyway.

wont hurt, may help!

TLyttle · Nov 04, 2009, 12:14 PM

Thanks, guys, I'll do that. What capacitance do I need? I have a bag of cute little 10s, and a few 221s. Thanks for your help!

groundfx · Nov 05, 2009, 01:38 AM

I tend to use .1 uf (marking would be 104.. how to read cap markings is here http://www.elecraft.com/Apps/caps.htm), but I've been told that in this application size doesn't matter too much and that 0.01 to .1 uf should work as long as they are non-polarized and they have a high enough voltage rating (all ceramic caps you're likely to have will be 50V or more which is fine.)

Your caps are 10 pf and 220 pf respectively. 0.01 uf is 10000 pf. So both are on the small size.

But if you don't have anything else available, I'd still try to 221's and then just do a range test. They might still work.

Dr Kiwi · Nov 06, 2009, 07:33 PM

Quote:

Originally Posted by TLyttle

Thanks, guys, I'll do that. What capacitance do I need? I have a bag of cute little 10s, and a few 221s. Thanks for your help!

Typically .047uF across the terminals and 0.010uF to the case.

TLyttle · Nov 11, 2009, 12:30 AM

Thanks again, guys, electronics are a huge mystery to me: if a hammer and wrench won't fix it, I'm lost...

groundfx · Nov 11, 2009, 12:42 AM

Quote:

Originally Posted by TLyttle

Thanks again, guys, electronics are a huge mystery to me: if a hammer and wrench won't fix it, I'm lost...

I'm glad to have helped. If you need any of those slightly larger caps, just send me a PM and I'll mail you some for free. I have bunch sitting here and I know to buy just a few can be a pain.

I seem to recall from past posts, you were a diesel guy. Are you taking a turn to the dark (electric) side?

TLyttle · Nov 12, 2009, 12:25 AM

Guilty as charged... I still am a diesel guy, but I was getting into electrics a couple of decades ago. I still build and fly both when I have the time, but so many projects are on my list, that time is limited. Now that I'm retired, I really do not understand how I had time to work!

I picked up some more caps, and they are in the higher numbers; will check them out against your referenced site. Thanks, groundfx, very helpful...

TLyttle · Nov 18, 2009, 10:46 PM

Groundfx is a great guy, thanks very much...

vintage1 · Nov 19, 2009, 06:54 AM

slight correction, size does matter.

Too big and especially it its a tubular type, and the inherent inductance means that they will be worse than a typical plate type ceramic.

Its important to remember a capacitor ALSO has series inductance and significant resistance in the case of an electrolytic or paper type.

This is the perfect application for disc ceramics. They are lousy on leakage (who cares) lousy on stability and tolerance (who cares), BUT they are very low series inductance. And can take heat that some of the plastic dielectrics cannot. Never use a polystyrene cap!

Self resonance you want up beyond 100Mhz for HF use.

I tend to use 10nF throughout.

Nov 04, 2009, 12:14 AM	#1
TLyttle Registered User Join Date: Mar 2004 Location: Keremeos, BC Canada Posts: 2,076	Old motor A buddy left me an old Simprop Pfalz kit, and I have a question about the motor: does it have internal capacitors, or do I need to add my own? It is a Simprop Speed 280, mounted in a ParcDrive 300+ gearbox. The instructions for the motor are in German... French, maybe; German, no chance!

Nov 05, 2009, 01:38 AM	#5
groundfx Registered User Join Date: Oct 2003 Location: Delta, BC, Canada Posts: 1,280	I tend to use .1 uf (marking would be 104.. how to read cap markings is here http://www.elecraft.com/Apps/caps.htm), but I've been told that in this application size doesn't matter too much and that 0.01 to .1 uf should work as long as they are non-polarized and they have a high enough voltage rating (all ceramic caps you're likely to have will be 50V or more which is fine.) Your caps are 10 pf and 220 pf respectively. 0.01 uf is 10000 pf. So both are on the small size. But if you don't have anything else available, I'd still try to 221's and then just do a range test. They might still work. Last edited by groundfx; Nov 05, 2009 at 01:54 AM.

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Nov 04, 2009, 04:55 AM	#3
vintage1 Replikit Designer Join Date: Sep 2002 Location: East Anglia, UK Posts: 27,384	just add three caps anyway. wont hurt, may help!

Nov 04, 2009, 12:14 PM	#4
TLyttle Registered User Join Date: Mar 2004 Location: Keremeos, BC Canada Posts: 2,076	Thanks, guys, I'll do that. What capacitance do I need? I have a bag of cute little 10s, and a few 221s. Thanks for your help!

Nov 11, 2009, 12:30 AM	#7
TLyttle Registered User Join Date: Mar 2004 Location: Keremeos, BC Canada Posts: 2,076	Thanks again, guys, electronics are a huge mystery to me: if a hammer and wrench won't fix it, I'm lost...

Nov 12, 2009, 12:25 AM	#9
TLyttle Registered User Join Date: Mar 2004 Location: Keremeos, BC Canada Posts: 2,076	Guilty as charged... I still am a diesel guy, but I was getting into electrics a couple of decades ago. I still build and fly both when I have the time, but so many projects are on my list, that time is limited. Now that I'm retired, I really do not understand how I had time to work! I picked up some more caps, and they are in the higher numbers; will check them out against your referenced site. Thanks, groundfx, very helpful...

Nov 18, 2009, 10:46 PM	#10
TLyttle Registered User Join Date: Mar 2004 Location: Keremeos, BC Canada Posts: 2,076	Groundfx is a great guy, thanks very much...

Nov 19, 2009, 06:54 AM	#11
vintage1 Replikit Designer Join Date: Sep 2002 Location: East Anglia, UK Posts: 27,384	slight correction, size does matter. Too big and especially it its a tubular type, and the inherent inductance means that they will be worse than a typical plate type ceramic. Its important to remember a capacitor ALSO has series inductance and significant resistance in the case of an electrolytic or paper type. This is the perfect application for disc ceramics. They are lousy on leakage (who cares) lousy on stability and tolerance (who cares), BUT they are very low series inductance. And can take heat that some of the plastic dielectrics cannot. Never use a polystyrene cap! Self resonance you want up beyond 100Mhz for HF use. I tend to use 10nF throughout.