RPi 5V PSU construction - Revision history

Pinoccio: Undo revision 233840 by Pwallis (talk) wrong place for this edit, this is not a power related discussion etc. but a PSU construction howto !

2013-06-05T10:57:41Z

Undo revision 233840 by Pwallis (talk) wrong place for this edit, this is not a power related discussion etc. but a PSU construction howto !

Pwallis: added introductory discussion of power requirements - usb std was from memory and I ought to check it...

2013-03-24T10:22:45Z

added introductory discussion of power requirements - usb std was from memory and I ought to check it...

Pinoccio: grammar ;)

2012-11-06T12:41:01Z

grammar ;)

Pinoccio: overvoltage protection circuit

2012-10-08T14:52:25Z

overvoltage protection circuit

Pinoccio: references, header/footer update

2012-10-05T12:46:55Z

references, header/footer update

Pinoccio: minor footer update

2012-10-05T09:53:24Z

minor footer update

Pinoccio: other PSU options - switched PSU

2012-10-05T00:13:49Z

other PSU options - switched PSU

Pinoccio: chapters reorganized

2012-08-09T09:55:52Z

chapters reorganized

Mcrocker: /* A 5V power supply for the Raspberry Pi - Construction How To */

2012-08-08T16:37:53Z

‎A 5V power supply for the Raspberry Pi - Construction How To

Pinoccio: small corrections

2012-07-30T14:21:52Z

small corrections

@@ Line 1: / Line 1: @@
 [[Category: RaspberryPi]]
 {{Template:RPi_Hardware}}
 == A 5V power supply for the Raspberry Pi - Construction How To ==

@@ Line 1: / Line 1: @@
 [[Category: RaspberryPi]]
 {{Template:RPi_Hardware}}
 == A 5V power supply for the Raspberry Pi - Construction How To ==

@@ Line 82: / Line 82: @@
 == Over-voltage protection ==
-Here is a nice upgrade for your PSU - a over-voltage protection circuit ''(see [http://blog.3b2.sk/igi/post/Tipy-a-triky-011-Prepatova-ochrana-Voltage-protect-Tips-tricks.aspx original post] in Slovak language)''. It can protect your device (RPi) from unwanted damage by high voltage from a faulty/malfunctioning PSU. In such case, it will short-circuit and burn it's fuse immediately.
+Here is a nice upgrade for your PSU - a over-voltage protection circuit ''(see [http://blog.3b2.sk/igi/post/Tipy-a-triky-011-Prepatova-ochrana-Voltage-protect-Tips-tricks.aspx original post] in Slovak language)''. It can protect your device (RPi) from unwanted damage by high voltage from a faulty/malfunctioning PSU. In such case, it will short-circuit and burn its fuse immediately.
 [[File:5v_overvoltage_protection.jpg|none]]
@@ Line 88: / Line 88: @@
 Steps:
 * choose appropriate fuse (according to expected load): 1-1.5A (fast type)
-* first don't put the fuse in it's holder - you have to initially adjust the circuit, so use a piece of wire (or you can use a lower-current fuse too if you don't mind spending/burning it during the adjustment process)
+* first don't put the fuse in its holder - you have to initially adjust the circuit, so use a piece of wire (or you can use a lower-current fuse too if you don't mind spending/burning it during the adjustment process)
-* set the 2k2 pot (trimmer) to it's max. value
+* set the 2k2 pot (trimmer) to its max. value
 * connect protection circuit to a power supply (if available a stabilized lab-PSU is preferred), set to 5.25V output (max. for USB; or exact 5V if you want) and 1-1.5A current limit
 * now slowly turn the 2k2 pot until the PSU's current-limiter goes on (or the fuse burns - if you chose that option)

← Older revision		Revision as of 14:52, 8 October 2012
Line 79:		Line 79:
	Connect this BEC to a 3S LiPo 5000mAh batter and you should get 15 hours of run time off one full charge.		Connect this BEC to a 3S LiPo 5000mAh batter and you should get 15 hours of run time off one full charge.
	You could also connect it directly to a 12v car battery for even longer run time.		You could also connect it directly to a 12v car battery for even longer run time.
		+
		+
		+	== Over-voltage protection ==
		+	Here is a nice upgrade for your PSU - a over-voltage protection circuit ''(see [http://blog.3b2.sk/igi/post/Tipy-a-triky-011-Prepatova-ochrana-Voltage-protect-Tips-tricks.aspx original post] in Slovak language)''. It can protect your device (RPi) from unwanted damage by high voltage from a faulty/malfunctioning PSU. In such case, it will short-circuit and burn it's fuse immediately.
		+
		+	[[File:5v_overvoltage_protection.jpg\|none]]
		+
		+	Steps:
		+	* choose appropriate fuse (according to expected load): 1-1.5A (fast type)
		+	* first don't put the fuse in it's holder - you have to initially adjust the circuit, so use a piece of wire (or you can use a lower-current fuse too if you don't mind spending/burning it during the adjustment process)
		+	* set the 2k2 pot (trimmer) to it's max. value
		+	* connect protection circuit to a power supply (if available a stabilized lab-PSU is preferred), set to 5.25V output (max. for USB; or exact 5V if you want) and 1-1.5A current limit
		+	* now slowly turn the 2k2 pot until the PSU's current-limiter goes on (or the fuse burns - if you chose that option)
		+	* well done, disconnect, now replace wire with your fuse and you're good to go

@@ Line 1: / Line 1: @@
-Back to the [[R-Pi Hub|Hub]].
+[[Category: RaspberryPi]]
-[[Category:RaspberryPi]]
+{{Template:RPi_Hardware}}
 == A 5V power supply for the Raspberry Pi - Construction How To ==
@@ Line 8: / Line 8: @@
-I have had problems with a cheap 5V/1A adapter from Ebay too (freezing, no LAN, etc.) ... The adapter could not provide enough power. It had 5.0xV unloaded, but with RaspberryPi connected I've measured 4.78V and less - dropping to 4.5V on TP1 and TP2, and that's not good. The voltage drop might be partially caused by the cable, but I've used a branded Nokia cable that looks pretty solid. Anyway, we have to compensate for that too. Also there is some voltage drop on the polyfuse F3, hence don't expect to get >=5.0V on TP1-TP2...<br />
+I have had problems with a cheap 5V/1A adapter from Ebay too (freezing, no LAN, etc.) ... The adapter could not provide enough power. It had 5.0xV unloaded, but with RaspberryPi connected I've measured 4.78V and less - dropping to 4.5V on TP1 and TP2 <ref>http://elinux.org/R-Pi_Troubleshooting#Troubleshooting_power_problems</ref>, and that's not good. The voltage drop might be partially caused by the cable, but I've used a branded Nokia cable that looks pretty solid. Anyway, we have to compensate for that too. Also there is some voltage drop on the polyfuse F3 (typically 0.1-0.2V, fuse should have about 0.2 Ohms <ref>http://www.raspberrypi.org/phpBB3/viewtopic.php?f=29&t=19033</ref>), hence don't expect to get >=5.0V on TP1-TP2...<br />
 <gallery>
 File:ebay_cheap_5V_adaptor1.jpg|Cheap PSU
@@ Line 14: / Line 14: @@
 </gallery>
-So instead of looking for another PSU (or cell phone charger), I decided to make my own PSU with the popular 7805 - 5V/1A regulator.
+So instead of looking for another PSU (or cell phone charger), I decided to make my own PSU with the popular 7805 - 5V/1A regulator <ref>http://www.learningaboutelectronics.com/Articles/What-is-a-LM7805-voltage-regulator</ref> <ref>http://www.circuitstune.com/2012/09/7805-voltage-regulator-circuit-7805-pinout.html</ref>. ''(There is also a 2A version available - 78'''S'''05)''
@@ Line 31: / Line 31: @@
 [[File:PSU_7805_v02.jpg|none]]
-Starting from left, we have a transformer (protected by a fuse - F1) supplying about 7-12V AC at 2A (use what you have at home or what is cheaper to buy). Next is a rectifier (or 4 diodes / >1A) with caps (C7-C10, for filtering). Now we should have approx. <AC voltage> x 1.41 - so if we have a 9V transformer, it will be about 12.69V. The 7805 needs at least 2V (depending on type/manufacturer) more on the input than on the output (I prefer using a little more, >3V to be sure) for stable regulation, and it can be up to 35V (but a big difference between input and output voltage means "a lot work" for the regulator and a lot heating). In this case, 8-9V DC measured after the rectifier would be optimal. Main filtering is ensured by C4 (use at least 1000uF for each 1A drawn), another filtering after the regulator is C3 (100-470uF). C1-C6 serve the 7805 for stable function and HF filtering. R1 and R2 adjust the voltage to 5.25V, as described before. D1 and D2 are for protection. A transil is used for over-voltage (peaks) protection on the output, a 5V8 type should be fine (5.8V reverse standoff voltage and approx. 6.2V breakdown voltage) - use P6KE6.8A or BZW06-5V8. For operation signaling (device on) a LED coupled with R3 is used. You may use another fuse on the output - F2.
+Starting from left, we have a transformer (protected by a fuse - F1) supplying about 7-12V AC at 2A (use what you have at home or what is cheaper to buy). Next is a rectifier (or 4 diodes / >1A) with caps (C7-C10, for filtering). Now we should have approx. <AC voltage> x 1.41 - so if we have a 9V transformer, it will be about 12.69V. The 7805 needs at least 2V<ref>http://en.wikipedia.org/wiki/78xx</ref> (depending on type/manufacturer) more on the input than on the output (I prefer using a little more, >=3V to be sure) for stable regulation, and it can be up to 35V (but a big difference between input and output voltage means "a lot work" for the regulator and a lot heating). In this case, 8-9V DC measured after the rectifier would be optimal. Main filtering is ensured by C4 (use at least 1000uF for each 1A drawn), another filtering after the regulator is C3 (100-470uF). C1-C6 serve the 7805 for stable function and HF filtering. R1 and R2 adjust the voltage to 5.25V, as described before. D1 and D2 are for protection. A transil is used for over-voltage (peaks) protection on the output, a 5V8 type should be fine (5.8V reverse standoff voltage and approx. 6.2V breakdown voltage) - use P6KE6.8A or BZW06-5V8. For operation signaling (device on) a LED coupled with R3 is used. You may use another fuse on the output - F2.
 This is a rather fancy circuit, you may simplify it if you like - by leaving out C7-C10, C5, C6, D1, D2, LED and R3, F2 (and the transil, if you don't want any protection). Or leave just some of them. Your choice ;)
@@ Line 50: / Line 50: @@
 [http://www.circuitstoday.com/variable-power-supply-using-7805 Variable power supply using 7805],<br />
 or [http://www.google.com/search?q=7805+regulator google more]
 === The testing prototype ===
-This is my testing prototype of this PSU, based on the first schematic. It's made of "what was found in the drawer". I've used an old 7805 regulator in TO3 package, C3 was taken from some broken mainboard, C4 is left out (it's not necessary, because the circuit is powered by a stable power supply from some old printer). The PSU provides stable 5.25V and i have 4.82V on TP1-TP2. My RaspberryPi works OK now :)<br />
+This is my testing prototype of this PSU, based on the first schematic. It's made of "what was found in the drawer". I've used an old 7805 regulator in TO3 package <ref>http://en.wikipedia.org/wiki/TO-3</ref>, C3 was taken from some broken mainboard, C4 is left out (it's not necessary, because the circuit is powered by a stable power supply from some old printer). The PSU provides stable 5.25V and i have 4.82V on TP1-TP2. My RaspberryPi works OK now :)<br />
 <gallery>
 File:RPi_5V_PSU_proto1_Pinoccio.jpg|5V PSU prototype
@@ Line 59: / Line 60: @@
 File:RPi_5V_PSU_proto4_Pinoccio.jpg|5V PSU prototype
 </gallery>
-I will make another PSU (for permanent operation) later - new 7805 in TO-220 package, appropriate heatsink, 1k resistor for R1 and a small pot for R2, new "fresh" caps and a transil, usb connector on PCB ... and I'll put it in some case.
+I will make another PSU (for permanent operation) later - new 7805 in TO-220 package <ref>http://en.wikipedia.org/wiki/TO-220</ref>, appropriate heatsink, 1k resistor for R1 and a small pot for R2, new "fresh" caps and a transil, usb connector on PCB ... and I'll put it in some case.
@@ Line 68: / Line 69: @@
 Simple switched PSU ''(with LM2576)'': [http://www.themagpi.com The MagPi - Issue 6] - page 8+9,<br />
-And more info on LM2576: [http://www.hobby-hour.com/electronics/lm2576-step-down-switching-regulator.php link], [http://wiringschematic.net/lm2576-switching-regulator/ link], [http://www.siongboon.com/projects/2005-08-07_lm2576_dc-dc_converter/ link]
+And more info on LM2576 <ref>http://www.ti.com/product/lm2576</ref> : [http://www.hobby-hour.com/electronics/lm2576-step-down-switching-regulator.php link], [http://wiringschematic.net/lm2576-switching-regulator/ link], [http://www.siongboon.com/projects/2005-08-07_lm2576_dc-dc_converter/ link]
@@ Line 80: / Line 81: @@
-----
+== References ==
-Back to the [[R-Pi Hub|Hub]].
+<references/>
-−
-−
-'''Hardware & Peripherals:'''
-−
-''[[RPi Hardware|Hardware]] and [[RPi HardwareHistory|Hardware History]].''
-''[[RPi Screens|Screens]], [[RPi Cases|Cases]] and [[RPi VerifiedPeripherals|Other Peripherals]].''
+{{Template:Raspberry Pi}}
-{{clear}}

← Older revision		Revision as of 09:53, 5 October 2012
Line 82:		Line 82:
	----		----
	Back to the [[R-Pi Hub\|Hub]].		Back to the [[R-Pi Hub\|Hub]].
		+
		+
		+	'''Hardware & Peripherals:'''
		+
		+	''[[RPi Hardware\|Hardware]] and [[RPi HardwareHistory\|Hardware History]].''
		+
		+	''[[RPi Low-level peripherals\|Low-level Peripherals]] and [[RPi Expansion Boards\|Expansion Boards]].''
		+
		+	''[[RPi Screens\|Screens]], [[RPi Cases\|Cases]] and [[RPi VerifiedPeripherals\|Other Peripherals]].''
		+	{{clear}}

← Older revision		Revision as of 00:13, 5 October 2012
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	~#Pinoccio		~#Pinoccio
		+
		+
		+	== Other PSU options ==
		+
		+	Simple switched PSU ''(with LM2576)'': [http://www.themagpi.com The MagPi - Issue 6] - page 8+9,<br />
		+	And more info on LM2576: [http://www.hobby-hour.com/electronics/lm2576-step-down-switching-regulator.php link], [http://wiringschematic.net/lm2576-switching-regulator/ link], [http://www.siongboon.com/projects/2005-08-07_lm2576_dc-dc_converter/ link]

@@ Line 1: / Line 1: @@
 Back to the [[R-Pi Hub|Hub]].
 [[Category:RaspberryPi]]
 == A 5V power supply for the Raspberry Pi - Construction How To ==
@@ Line 30: / Line 21: @@
 [[File:PSU_7805_v01.jpg|none]]
-The resistors R1 and R2 serve as adjustment of the output voltage. The formula is:  ''V out = V fixed + { R2 [ (V fixed/R1) + I standby] }'', where ''V fixed=5V'' and ''I standby=2.5mA'' (for 7805). I calculated for resistors that I had at home, but for best results R1 should be about 470ohm to 1k. Remember that resistors have some tolerance, so results may vary slightly, always measure. Value of C3 is not critical, I recommend 100-470uF. Same for C4, where for every 1A drawn, use 1000uF of capacity (and add some reserve). Don't forget to put C1 and C2 as close as possible to the regulator. And a heatsink for the regulator is necessary too.
+The resistors R1 and R2 serve as adjustment of the output voltage (~ 5.25V). The formula is:  ''V out = V fixed + { R2 [ (V fixed/R1) + I standby] }'', where ''V fixed=5V'' and ''I standby=2.5mA'' (for 7805). I calculated for resistors that I had at home, but for best results R1 should be about 470ohm to 1k. Remember that resistors have some tolerance, so results may vary slightly, always measure. Value of C3 is not critical, I recommend 100-470uF. Same for C4, where for every 1A drawn, use 1000uF of capacity (and add some reserve). Don't forget to put C1 and C2 as close as possible to the regulator. And a heatsink for the regulator is necessary too.
 ''I've used an old 9.5V/1500mA power supply from an printer as the source for this regulator, so no transformer and rectifier etc. was needed in my case. And it works just fine :)''
@@ Line 72: / Line 63: @@
 ~#Pinoccio
 ----
 Back to the [[R-Pi Hub|Hub]].